JP7109877B2 - Multicolor printing system and control method - Google Patents

Description

The present invention relates to a multicolor printing system and control method.

2. Description of the Related Art A multicolor printing system is known in which a plurality of printing units are installed along a web transport path, plate cylinders provided in each printing unit are individually rotationally driven, and the web is sequentially printed. In a multi-color printing system, registration marks printed on the web are detected, and based on the detection results, the amount of misregistration in the printing position between the plate cylinders (the amount of misregistration) is calculated, and the plate cylinders are adjusted to correct the misregistration. to control the drive motor of the

JP-A-08-052865

In a multicolor printing system, changing the web transport speed (ie, printing speed) causes the web tension to vary due to the moment of inertia of the free rolls between the plate cylinders. Variation in tension can cause misregistration.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique capable of reducing the influence of changes in web transport speed on misregistration.

In order to solve the above problems, a multi-color printing system according to one aspect of the present invention is a multi-color printing system that prints on a web using a plurality of plate cylinders, and determines whether or not the conveying speed of the web is changing. and a suspension unit that controls the plurality of plate cylinders so that the print patterns printed on the web by the plurality of plate cylinders do not deviate according to the determination result of the determination unit.

Another aspect of the invention is a control method. This method is a method executed in a multi-color printing system that prints on a web using a plurality of plate cylinders, and includes the step of determining whether or not the conveying speed of the web is changing; and controlling the plurality of plate cylinders so that the print patterns printed on the web by the plate cylinders are not misaligned.

Arbitrary combinations of the above constituent elements, and mutual substitution of the constituent elements and expressions of the present invention in methods, devices, systems, etc. are also effective as aspects of the present invention.

According to the present invention, it is possible to reduce the influence of changes in web transport speed on misregistration.

1 is a diagram showing the configuration of a multicolor printing system according to an embodiment; FIG. 2 is a block diagram showing the functions and configuration of a registration control unit in FIG. 1; FIG.

Hereinafter, the same or equivalent constituent elements, members, and steps shown in each drawing are denoted by the same reference numerals, and redundant description will be omitted as appropriate. In addition, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding. Also, in each drawing, some of the members that are not important for explaining the embodiments are omitted.

FIG. 1 shows the configuration of a multicolor printing system 100 according to an embodiment. The multicolor printing system 100 includes a first printing unit 10A, a second printing unit 10B, a third printing unit 10C, a fourth printing unit 10D (hereinafter collectively referred to as “printing units 10”), and a plurality of free rolls 20. and a register control unit 30 .

The web 2 is unwound from an unwinding roll (not shown) by an infeed roll (not shown), guided by a free roll 20, conveyed in a predetermined direction, and wound up by a take-up roll (not shown). The first printing unit 10A, the second printing unit 10B, the third printing unit 10C, and the fourth printing unit 10D are installed in this order along the transport direction of the web 2 .

The first printing unit 10A includes a plate cylinder 11A, an impression cylinder 12A, and a drive motor 13A. The plate cylinder 11A is pressed against the web 2 by the impression cylinder 12A. The web 2 is printed with a printing pattern and register marks of colors corresponding to the plate cylinder 11A. The drive motor 13A rotationally drives the plate cylinder 11A.

The second printing unit 10B includes a plate cylinder 11B, an impression cylinder 12B, and a drive motor 13B. The third printing unit 10C includes a plate cylinder 11C, an impression cylinder 12C, and a drive motor 13C. The fourth printing unit 10D includes a plate cylinder 11D, an impression cylinder 12D and a drive motor 13D.

Plate cylinder 11B, plate cylinder 11C, and plate cylinder 11D are configured in the same manner as plate cylinder 11A. The impression cylinder 12B, the impression cylinder 12C, and the impression cylinder 12D are constructed in the same manner as the impression cylinder 12A. The drive motor 13B, the drive motor 13C, and the drive motor 13D are configured similarly to the drive motor 13A. Multicolor printing system 100 is a sectional drive type printing system in which each plate cylinder is driven by a separate drive motor.

The plate cylinder 11A, the plate cylinder 11B, the plate cylinder 11C, and the plate cylinder 11D are also collectively referred to as the plate cylinder 11 below. The impression cylinder 12A, the impression cylinder 12B, the impression cylinder 12C, and the impression cylinder 12D are also collectively called the impression cylinder 12. As shown in FIG. The drive motor 13A, the drive motor 13B, the drive motor 13C, and the drive motor 13D are also collectively called the drive motor 13. Also, the registration marks printed by the first printing unit 10A, the second printing unit 10B, the third printing unit 10C, and the fourth printing unit 10D are respectively the first registration mark, the second registration mark, the third registration mark, and the third registration mark. 4 It is called a registration mark.

The register control unit 30 includes a mark sensor 40B, a mark sensor 40C, a mark sensor 40D (hereinafter collectively referred to as "mark sensor 40"), a speed detector 42, a plurality of tension detectors 44, a control device 50 and including.

The speed detector 42 detects the transport speed (that is, printing speed) of the web 2 at a predetermined cycle (for example, one second cycle). Note that the speed detector 42 may detect the transport speed of the web 2 by detecting the rotation speed of the infeed roll.

A plurality of tension detectors 44 detect the tension of the web 2 between the plate cylinders at predetermined intervals (for example, intervals of one second). A differential transformer or a load cell is generally used as the tension detector, but the tension detector is well known and will not be described in detail here.

The mark sensor 40B is provided downstream of the second printing unit 10B. The mark sensor 40B has an upstream first photodetector element T1 and a downstream second photodetector element T2. The first photodetector T1 and the second photodetector T2 are arranged with an interval L therebetween. The interval L corresponds to the distance between the first register mark and the second register mark when there is no misregistration. Therefore, if the first register mark and the second register mark are printed at regular positions with the interval L, they are detected at substantially the same timing by the first photodetector element T1 and the second photodetector element T2. .

The mark sensor 40C and the mark sensor 40D are configured similarly to the mark sensor 40B. If the second register mark and the third register mark are printed at regular positions with the interval L, they are detected at substantially the same timing by the first photodetector element T1 and the second photodetector element T2 of the mark sensor 40C. be done. Further, if the third register mark and the fourth register mark are printed at regular positions with the interval L, substantially the same timing is detected by the first photodetector element T1 and the second photodetector element T2 of the mark sensor 40D. detected by

FIG. 2 is a block diagram showing the functions and configuration of the control device 50. As shown in FIG. Each block shown here can be implemented by hardware such as a computer CPU (central processing unit) or other elements or mechanical devices, and is implemented by software such as a computer program. The functional blocks realized by their cooperation are drawn. Therefore, those skilled in the art who have read this specification will understand that these functional blocks can be implemented in various ways by combining hardware and software.

The control device 50 includes a registration mark detection section 51 , a misregistration amount calculation section 52 , an acceleration calculation section 54 , a determination section 55 , a trend prediction section 56 and a registration section 57 . The register mark detection unit 51 detects the register marks provided on the web 2 based on the signal output from the mark sensor 40 .

The detection result by the registration mark detection unit 51 is input to the misregistration amount calculation unit 52 . The misregistration amount calculation unit 52 calculates the amount of misregistration of the printing positions between the printing units, that is, the amount of misregistration based on the detection result. Specifically, for example, the first register mark and the second register mark are printed at an interval L when there is no misregistration. Further, as described above, the first photodetector element T1 and the second photodetector element T2 of the mark sensor 40B are also arranged with the interval L therebetween. Therefore, when there is no misregistration, the first and second registration marks are detected at substantially the same timing. On the other hand, when misregistration occurs, the first and second registration marks are detected at different timings. The misregistration amount calculator 52 calculates a value obtained by multiplying the difference in detection timing by the conveying speed of the web 2 as the misregistration amount.

In order to change the printing speed, the rotational speed of the in-feed roll may be accelerated or decelerated (hereinafter also collectively referred to as “acceleration/deceleration”) to accelerate/decelerate the conveying speed of the web 2 . The acceleration calculator 54 calculates the acceleration of the transport speed of the web 2 by differentiating the transport speed of the web 2 obtained from the speed detector 42 .

The determination unit 55 determines whether or not the transport speed of the web 2 is accelerating or decelerating, that is, whether or not the transport speed of the web 2 is changing. The determination unit 55 determines that the conveying speed of the web 2 is accelerating when the acceleration calculated by the acceleration calculation unit 54 is a positive value, and determines that the web 2 is accelerated when the acceleration calculated by the acceleration calculation unit 54 is a negative value. 2 is decelerating, and the acceleration calculated by the acceleration calculator 54 is substantially zero, the transport speed of the web 2 is neither accelerating nor decelerating (i.e., the transport speed is constant). ).

The trend prediction unit 56 predicts the trend of change in the conveying speed of the web 2 . In the present embodiment, the trend prediction unit 56 calculates the differential value of the acceleration calculated by the acceleration calculation unit 54 as the predicted value.

The alignment section 57 controls each printing cylinder 11 so that the printing patterns printed on the web 2 by each printing cylinder 11 of each printing unit 10 do not deviate.

First, the offset unit 57 determines the initial phase of each plate cylinder based on the circumference of the plate cylinder and the path length between the plate cylinders. Here, when the path length from the printing point P on the printing cylinder 11A to the printing point P on the printing cylinder 11B is an integer multiple of the circumference of the printing cylinder 11, if the printing cylinders 11A and 11B are in phase, , no misregistration occurs between them. On the other hand, if it is not an integral multiple, and the plate cylinders 11A and 11B are set in the same phase, misregistration occurs by the remainder of the path length divided by the circumference. The same applies to plate cylinder 11B and plate cylinder 11C, and plate cylinder 11C and plate cylinder 11D. The registering unit 57 considers these and determines the initial phase of each plate cylinder so as not to cause misregistration. Since the technique for determining the initial phase is publicly known, further explanation will be omitted.

Further, when misregistration occurs between the printing units, that is, when misregistration is calculated by the misregistration amount calculator 52, the misregistration unit 57 controls the plate cylinder 11 to reduce the misregistration.

Here, when the phase of the plate cylinder 11 is manipulated to reduce misregistration, the tension of the web 2 in front of and behind the plate cylinder 11 varies. Therefore, if the phase of the plate cylinder 11 is manipulated to reduce the misregistration, misregistration will occur in subsequent stages. For example, if misregistration occurs between the first printing unit 10A and the second printing unit 10B, manipulating the phase of the plate cylinder 11B of the second printing unit 10B will cause tension in the web 2 in front of and behind the plate cylinder 11B. , resulting in misregistration between the second printing unit 10B and the third printing unit 10C.

Therefore, the misregistration unit 57 adjusts the plate cylinders 11 so that, if misregistration occurs between any of the printing units, all the printing units cooperate to correct the misregistration. to control. For example, when there is a misregistration between the first printing unit 10A and the second printing unit 10B, the registering section 57 first calculates the amount of misregistration between the first printing unit 10A and the second printing unit 10B. A control signal is generated to be output to the drive motor 13B of the plate cylinder 11B in order to reduce it. Subsequently, the misregistration unit 57 calculates the amount of misregistration that will occur between the second printing unit 10B and the third printing unit 10C due to tension fluctuations caused by manipulating the phase of the plate cylinder 11B, and calculates the amount of misregistration. A control signal is generated to be output to the drive motor 13C of the plate cylinder 11C to reduce the amount. Further, the misregistration unit 57 calculates the amount of misregistration that will occur between the third printing unit 10C and the fourth printing unit 10D due to the change in tension caused by manipulating the phase of the plate cylinder 11C, and calculates the amount of misregistration. A control signal to be output to the drive motor 13D of the plate cylinder 11D is generated in order to reduce the . The suspension unit 57 outputs each control signal thus generated to each drive motor 13 of each printing unit 10 .

Subsequently, when the conveying speed of the web 2 is accelerated or decelerated in order to change the printing speed, the moment of inertia of the free roll 20 changes the tension of the web 2 between the plate cylinders. In general, variations in tension can cause misregistration. That is, the acceleration/deceleration of the conveying speed of the web 2 causes misregistration.

On the other hand, when the determination unit 55 determines that acceleration/deceleration is being performed, the suspension unit 57 estimates (calculates) the tension fluctuation that is likely to occur between the plate cylinders due to the acceleration/deceleration based on the acceleration. Estimate (calculate) the misregistration that may occur due to tension fluctuations. Then, the registering unit 57 generates a control signal to be output to the drive motor 13 of the plate cylinder 11 so as to suppress the occurrence of the estimated misregistration. That is, when the determination unit 55 determines that acceleration/deceleration is being performed, the misregistration unit 57 calculates the misregistration amount after the misregistration amount is calculated by the misregistration amount calculation unit 52 when the misregistration caused by the acceleration/deceleration is actually occurring. Instead of controlling each plate cylinder 11 to reduce the amount of misregistration, a control signal to be output to the drive motor 13 is generated so as to suppress the occurrence of misregistration caused by acceleration/deceleration. In other words, when the determination unit 55 determines that acceleration/deceleration is being performed, the alignment unit 57 performs feedforward control so that misregistration due to acceleration/deceleration does not occur.

The suspension unit 57 preferably estimates (calculates) the acceleration at the timing of outputting the control signal to each drive motor 13 based on the predicted value from the trend prediction unit 56 . The suspension unit 57 estimates tension fluctuations that will occur between the plate cylinders due to acceleration/deceleration based on this estimated acceleration.

According to the multicolor printing system 100 according to the embodiment described above, it is determined whether or not the conveying speed of the web 2 is accelerating or decelerating. , the phase of each plate cylinder 11 of each printing unit 10 is adjusted. In other words, the phase of each plate cylinder 11 of each printing unit 10 is adjusted in consideration of the change in tension caused by the acceleration/deceleration of the transport speed of the web 2 . As a result, it is possible to shorten the time required for the misregistration between all the plate cylinders to converge when the speed of conveying the web 2 is accelerated or decelerated. Also, the amount of misregistration during acceleration and deceleration is reduced.

Further, according to the multi-color printing system 100 according to the embodiment, when the transport speed of the web 2 is changing, at the timing of outputting the control signal to the drive motor 13 based on the predicted value from the trend prediction unit 56, That is, the acceleration at the timing when the plate cylinder 11 is controlled is estimated. Then, based on the estimated acceleration, the tension variation and thus the amount of misregistration are estimated. In this case, since the amount of misregistration can be estimated more accurately, it is possible to shorten the time until the misregistration between all the plate cylinders converges when the conveying speed of the web 2 is accelerated or decelerated.

The multi-color printing system according to the embodiment has been described above. It should be understood by those skilled in the art that this embodiment is merely an example, and that various modifications can be made to combinations of each component and each treatment process, and that such modifications are within the scope of the present invention. be. Modifications are shown below.

(Modification 1)
In the embodiment, the case where the multicolor printing system 100 includes four printing units of the first printing unit 10A, the second printing unit 10B, the third printing unit 10C, and the fourth printing unit 10D has been described, but the present invention is not limited to this. , two or more printing units.

(Modification 2)
The method of calculating the amount of misregistration is not limited to the calculation method of the embodiment. Those skilled in the art will appreciate that the amount of misregistration can be calculated by other calculation methods. For example, the misregistration amount may be calculated using a photographed image of the register mark.

Any combination of the above-described embodiments and modifications is also useful as embodiments of the present invention. A new embodiment resulting from the combination has the effects of the combined embodiment and modifications.

2 web 10 printing unit 10A first printing unit 10B second printing unit 10C third printing unit 10D fourth printing unit 11 plate cylinder 13 drive motor 22 free roll 50 controller 51 register mark Detection unit 52 Misregister amount calculation unit 54 Acceleration calculation unit 55 Judgment unit 56 Trend prediction unit 57 Stop unit 100 Multicolor printing system.

Claims (2)

A multicolor printing system for printing on a web with multiple plate cylinders, comprising:
a plurality of guide members disposed between each plate cylinder and guiding the web;
A judging unit that calculates a web conveyance acceleration based on a differential value of the web conveyance speed when the printing speed is changed, and judges whether or not the web conveyance speed has changed based on the web conveyance acceleration. When,
a tendency prediction unit that predicts the web conveyance acceleration based on the differential value of the web conveyance acceleration;
When the judging unit judges that the web conveying speed has changed, based on the web conveying acceleration by the judging unit, the differential value of the web conveying acceleration by the trend predicting unit, and the moment of inertia of the guide member calculating a misregister amount of the web, and based on the misregister amount, the plurality of plates so as not to cause misalignment of the printing patterns printed on the web by the plurality of plate cylinders due to acceleration/deceleration of the web conveyance speed; a shift unit for individually manipulating the phases of all the plate cylinders after the first plate cylinder and the second plate cylinder after the first plate cylinder ;
with
The offset section reduces additional misregistration due to cascading tension variations applied to all subsequent plate cylinders by individually manipulating the phases of all plate cylinders subsequent to the second plate cylinder. A multi-color printing system characterized by generating a control signal to control the phases of the plurality of plate cylinders , and using the control signal to control the phases of all the plate cylinders downstream of the plate cylinder whose phase has been manipulated. 1. A method practiced in a multicolor printing system for printing on a web guided by a plurality of plate cylinders by a plurality of guide members interposed between the plate cylinders , comprising:
calculating a web transport acceleration based on a differential value of the web transport speed when the printing speed is changed, and determining whether or not the web transport speed has changed based on the web transport acceleration; ,
predicting the web conveyance acceleration based on the differential value of the web conveyance acceleration;
When it is determined that the web transport speed has changed in the determining step , the web transport acceleration in the determining step , the differential value of the web transport acceleration in the predicting step, and the moment of inertia of the guide member and calculating the amount of misregistration of the web based on the amount of misregistration so that the print pattern printed on the web by the plurality of plate cylinders does not deviate due to the acceleration or deceleration of the conveying speed of the web. a step of individually manipulating the phases of all of the plurality of plate cylinders after the first plate cylinder, the second plate cylinder and the subsequent plate cylinders ;
In the manipulating step, the phase of all plate cylinders after the second plate cylinder is individually manipulated to reduce additional misregistration due to cascading tension variations applied to all subsequent plate cylinders. A control method , comprising: generating a control signal to be controlled, and using the control signal to manipulate the phases of all the plate cylinders subsequent to the phase- controlled plate cylinder among the plurality of plate cylinders.

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