Print control device, print control method, and print control program

Abstract

To provide a printing control device and the like that can properly start additional printing.SOLUTION: A printing control device 40, which controls a printing device 10 that is provided with an inkjet printing part 11 comprising a printing nozzle 111 that discharges ink to a printed matter 50 being conveyed and an additional printing part 12 that applies additional printing to the printed matter 50 at a rear stage of the inkjet printing part 11, is further provided with: a reference point sensing part 41 that senses a reference point on a rotational trajectory of a main conveying roller 112 that conveys the printed matter 50 by rotating, in the inkjet printing part 11; an inkjet printing starting part 42 that starts printing on the printed matter 50 by the printing nozzle 111, in accordance with a sensed result of the sensed reference point; and an additional printing starting position calculating part 43 that calculates an additional printing starting position in the printed matter 50 by the additional printing part 12, in accordance with the sensed result of the reference point.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a print control device and the like. [Background technology]

[0002] Known printing devices that print on sheet-like substrates such as rolled paper include inkjet printing devices such as those described in Patent Document 1. Printing nozzles of each color, such as cyan (C), magenta (M), yellow (Y), and black (K), eject ink of that color onto the substrate, which is transported by rotating transport rollers or the like, to print a desired image.

[0003] A substrate that has been subjected to a primary printing of each color using an inkjet printing device may then undergo a secondary printing (hereinafter also referred to as "reprinting") using another coating such as varnish (or varnish) for surface protection. In such cases, it is necessary to appropriately determine the start position and / or start timing of the secondary printing on the substrate (hereinafter collectively referred to as "reprinting start position") to prevent misalignment between the primary printing and the secondary printing (hereinafter also referred to as "register error," and the position control of each subsequent printing to reduce register error is also referred to as "register control").

[0004] For example, a mark sensor that detects register control marks, such as register marks, printed during primary printing for register control purposes can be used to appropriately determine the overprinting start position. Specifically, when a transport roller or the like in an inkjet printing device transports a substrate at a constant transport speed (hereinafter also referred to as the "production speed"), the inkjet printing device prints register control marks for the primary printing at constant (spatial) intervals, and the mark sensor detects these register control marks at constant (temporal) intervals. Based on these constant detection intervals, the timing at which each register control mark of the primary printing arrives at the secondary printing unit (overprinting unit) can be accurately determined, allowing the start position of the secondary printing (overprinting start position) relative to the primary printing to be appropriately determined. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-181874 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when printing begins, the inkjet printing device's transport rollers and other components must accelerate to production speed. During this acceleration period, the (spatial) intervals at which the inkjet printing device prints the primary print register control marks and / or the (time) intervals at which the mark sensor detects the register control marks are not constant, making it impossible to properly determine the overprint start position, as described above. As a result, there is a risk that secondary printing (overprinting) cannot be properly started on the primary printed substrate that is transported at an inconstant speed until the transport rollers and other components reach a constant production speed. In such cases, the primary printed substrate that did not undergo proper secondary printing (overprinting) is wasted. If the substrate is paper, this results in a large amount of so-called wasted paper.

[0007] The present invention has been made in view of the above circumstances, and has an object to provide a print control device and the like that can appropriately start additional printing. [Means for solving the problem]

[0008] In order to solve the above problem, one embodiment of the printing control device of the present invention is a printing control device that controls a printing device that has an inkjet printing unit equipped with printing nozzles that eject ink onto a substrate being transported, and an overprinting unit that applies overprinting to the substrate downstream of the inkjet printing unit, and in the inkjet printing unit, it has a reference point detection unit that detects a reference point on the rotational orbit of the rotary transport unit that transports the substrate by rotation, an inkjet printing start unit that starts printing on the substrate by the printing nozzle in response to the detection of the reference point, and an overprinting start position calculation unit that calculates the start position of overprinting on the substrate by the overprinting unit in response to the detection of the reference point.

[0009] In this aspect, printing (primary printing) is initiated by the printing nozzles in response to detection of a reference point on the rotary conveyor in the inkjet printing unit, and the overprinting start position is calculated by the overprinting unit (secondary printing unit). In contrast to the method using the mark sensor described above, which determines the overprinting start position when the printed material reaches production speed as a trigger, this aspect allows calculation of the overprinting start position to be initiated when the inkjet printing unit detects a reference point on the rotary conveyor. This allows the overprinting start position to be determined quickly and overprinting to begin appropriately regardless of the conveyance speed of the printed material. This reduces waste of printed material (such as wasted paper) due to delays in determining the overprinting start position.

[0010] Another aspect of the present invention is a printing control method for controlling a printing device that includes an inkjet printing unit with print nozzles that eject ink onto a transported print substrate, and an overprinting unit that performs overprinting on the print substrate downstream of the inkjet printing unit, the method including a reference point detection step in the inkjet printing unit that detects a reference point on a rotational path of a rotary transport unit that transports the print substrate by rotation, an inkjet printing start step that starts printing on the print substrate by the print nozzles in response to the detection of the reference point, and an overprinting start position calculation step that calculates an overprinting start position on the print substrate by the overprinting unit in response to the detection of the reference point.

[0011] Any combination of the above components and any conversion of these expressions into methods, devices, systems, recording media, computer programs, etc. are also encompassed by the present invention. [Effects of the Invention]

[0012] According to the present invention, additional printing can be started appropriately. [Brief explanation of the drawings]

[0013] [Figure 1] 1 illustrates a schematic configuration of a printing device controlled by a print control device. [Figure 2]10A and 10B are schematic diagrams illustrating an example of detection of a reference point on the circumference of a main transport roller by an encoder. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a mode for carrying out the present invention (hereinafter also referred to as an embodiment) will be described in detail with reference to the drawings. In the description and / or drawings, identical or equivalent components, members, processes, etc. will be assigned the same reference numerals, and redundant explanations will be omitted. The scale and shape of each part shown in the drawings are set for convenience to simplify the explanation, and should not be interpreted as limiting unless otherwise specified. The embodiment is an example and does not limit the scope of the present invention in any way. All features and combinations thereof described in the embodiment are not necessarily essential to the present invention.

[0015] FIG. 1 is a schematic diagram illustrating a configuration of a printing apparatus 10 controlled by a print control device 40 according to an embodiment of the present invention. The printing apparatus 10 performs primary printing by an inkjet printing unit 11 and secondary printing (overprinting) by an overprinting unit 12 on a sheet-like substrate 50, such as a roll of paper or a web wound around a rotating shaft 60. While any paint can be used in the inkjet printing unit 11 and the overprinting unit 12, in this embodiment, the inkjet printing unit 11 uses inks of various colors, such as cyan (C), magenta (M), yellow (Y), and black (K), as the primary printing paint, and the overprinting unit 12 uses a varnish for surface protection as the secondary printing paint (overprinting paint). FIG. 1 schematically illustrates primary patterns P1 of various colors printed by the inkjet printing unit 11 and secondary patterns P2 of varnish printed by the overprinting unit 12. The inkjet printing unit 11 and the overprinting unit 12 print the respective patterns P1 and P2 on the printing substrate 50 for each unit printing length (hereinafter also referred to as "repeat length") equivalent to the printing surface or paper surface of one page in the transport direction (roughly from left to right in Figure 1) of the printing substrate 50 unwound from the rotary shaft 60. In the ideal state shown in Figure 1, there is no printing misalignment (register error) between the primary pattern P1 and the secondary pattern P2.

[0016] The inkjet printing unit 11 has one or more print nozzles 111 that eject ink of each color onto the transported printing substrate 50. In the example of FIG. 1, three print nozzles 111, 111A, 111B, and 111C, are schematically shown as the print nozzles 111. The multiple print nozzles 111A, 111B, and 111C typically eject ink of different colors onto the printing substrate 50. The number of print nozzles 111 is arbitrary; for example, by providing four print nozzles 111, full-color printing can be performed onto the printing substrate 50 using the four common colors of ink: cyan (C), magenta (M), yellow (Y), and black (K).

[0017] The inkjet printing unit 11 includes a main transport roller 112 and one or more sub-transport rollers 113 as a transport unit or rotary transport unit that transports the printing substrate 50 in the transport direction during inkjet printing by the print nozzle 111. The main transport roller 112 is a roller that transports the printing substrate 50 at a position opposite the print nozzle 111, and is driven to rotate in a clockwise direction in FIG. 1 by a drive motor (not shown). The size (specifically, radius and circumference) of the main transport roller 112 is arbitrary, but for example, if the circumference of the main transport roller 112 is N times the repeat length (N is a natural number), the print nozzle 111 prints the primary pattern P1 N times on the printing substrate 50 during one rotation of the main transport roller 112.

[0018] The print nozzle 111 itself and / or the printing location (the location where ink is ejected) by the print nozzle 111 may be movable in a direction intersecting the transport direction of the substrate 50 (a direction roughly from top to bottom at the position facing the print nozzle 111 in FIG. 1). For example, the print nozzle 111 and / or the printing location may be movable back and forth in a direction perpendicular to the transport direction of the substrate 50 (a direction perpendicular to the plane of the paper in FIG. 1). In this case, the reciprocating movement speed or scanning speed of the print nozzle 111 and / or the printing location is greater than the transport speed of the substrate 50 that intersects or is perpendicular thereto.

[0019] Specifically, while the printing substrate 50 is transported by one pixel in the transport direction (hereinafter also referred to as the "vertical direction"), the printing nozzle 111 and / or the printing location scans all pixels in the scanning direction (hereinafter also referred to as the "horizontal direction"), and ink is selectively ejected onto the pixel location where printing is to be performed. To ensure that this inkjet printing is performed appropriately, the scanning speed or printing speed of the printing nozzle 111 and / or the printing location is adaptively controlled in accordance with the transport speed of the printing substrate 50 or the rotation speed of the main transport roller 112. Alternatively, the scanning speed of the printing nozzle 111 and / or the printing location may be constant, with a stop period or standby period between each horizontal scan that is in accordance with the transport speed of the printing substrate 50 or the rotation speed of the main transport roller 112. Alternatively, the scanning speed or stop period of the printing nozzle 111 and / or the printing location may be constant regardless of the transport speed of the printing substrate 50 or the rotation speed of the main transport roller 112. In this case, while the transport speed of the printing substrate 50 is not reaching the production speed, a vertically squashed primary pattern P1 is printed by the printing nozzle 111. In addition, the vertical (spatial) interval of the register marks (described below) printed by the printing nozzle 111 together with the primary pattern P1 also becomes shorter than the intended predetermined interval.

[0020] The sub-conveyor rollers 113 transport the printing substrate 50 in conjunction with the main transport rollers 112. In the example of Fig. 1, a first sub-conveyor roller 113A arranged in front of the main transport rollers 112 and a second sub-conveyor roller 113B arranged in back of the main transport rollers 112 are schematically shown. Each sub-conveyor roller 113 may be driven to rotate in the counterclockwise direction in Fig. 1 by a drive motor (not shown), or may be a driven roller that rotates in the counterclockwise direction in accordance with the clockwise rotation of the main transport rollers 112.

[0021] A speed control unit 20 is provided between the inkjet printing unit 11 and the overprinting unit 12 to control the transport speed of the printing substrate 50. The speed control unit 20 detects the current transport speed of the printing substrate 50 based on the detection interval of marks such as register marks by the mark sensor 21. The register marks are register control marks that the inkjet printing unit 11 prints in the margins or the like for each repeat length (unit print length) for register control by the register control unit 30, which will be described later. Therefore, the current transport speed of the printing substrate 50 can be obtained by dividing the known repeat length set in the printing device 10 by the detection interval of register marks such as those detected by the mark sensor 21.

[0022] If the horizontal scanning speed of the printing nozzle 111 is constant regardless of the vertical transport speed of the printing substrate 50, the vertical spacing of the register marks printed by the printing nozzle 111 will not match the known repeat length while the transport speed of the printing substrate 50 has not reached the production speed. In this case, the speed control unit 20 can accurately detect the transport speed of the printing substrate 50 only after the transport speed of the printing substrate 50 has reached the production speed. The speed control unit 20 compares the detected current transport speed of the printing substrate 50 with a target transport speed (e.g., production speed) provided by a higher-level controller (not shown) and applies a current or the like to the drive motor 22 to reduce the difference. As a result, the transport roller 23, driven by the drive motor 22, rotates at a speed closer to the target transport speed than the current transport speed, transporting the printing substrate 50.

[0023] The overprinting unit 12, which performs overprinting (secondary printing) on ​​the printing substrate 50 after the inkjet printing unit 11, includes a plate cylinder 121 and an impression cylinder 122. The plate cylinder 121, around which a printing plate for the secondary image P2 is wound, is rotated clockwise in FIG. 1 by a drive motor 32 to print the secondary image P2 on the printing substrate 50. Typically, the circumference of the plate cylinder 121 and / or the printing plate is equal to the repeat length (unit printing length), and the secondary image P2 is printed once on the printing substrate 50 during one rotation of the plate cylinder 121. The impression cylinder 122 presses the printing substrate 50 against the plate cylinder 121, generating a printing pressure (printing pressure) appropriate for printing the secondary image P2 by the plate cylinder 121. Note that the overprinting unit 12 may be a printing unit of another type that does not use the plate cylinder 121 and impression cylinder 122 (for example, an inkjet printing unit such as the inkjet printing unit 11). Similar to the inkjet printing unit 11, the overprinting unit 12 prints register marks for each repeat length for register control by the register control unit 30, which will be described later. On each printing surface or page, the primary register marks produced by the primary printing (inkjet printing unit 11) and the secondary register marks produced by the secondary printing (overprinting unit 12) are printed at predetermined intervals along the transport direction of the printing substrate 50.

[0024] The registration control unit 30 detects the printing misalignment (register error) between the primary image P1 and the secondary image P2 as a deviation from the predetermined spacing between the primary and secondary register marks, and controls the phase (rotational position) of the plate cylinder 121 using the drive motor 32 to reduce the misalignment. The spacing between the primary and secondary register marks in the transport direction is detected by a mark sensor 31 located downstream of the plate cylinder 121. The mark sensor 31 has two detectors, such as photodetectors, that can simultaneously detect the primary and secondary register marks. The spacing between these two detectors in the transport direction is approximately equal to the intended spacing (predetermined spacing) between the primary and secondary register marks. Therefore, while one detector detects the primary register mark, the other detector detects the secondary register mark. If the spacing between the primary and secondary register marks detected by the mark sensor 31 deviates from the predetermined spacing, the registration control unit 30 applies a current or other signal to the drive motor 32 to reduce the printing misalignment (register error).

[0025] The print control device 40 according to this embodiment for controlling the above-described printing device 10 includes a reference point detection unit 41, an inkjet printing start unit 42, and an overprint start position calculation unit 43. These functional blocks are realized through the cooperation of hardware resources, such as the computer's central processing unit, memory, input devices, output devices, and peripheral devices connected to the computer, and software executed using these resources. Regardless of the type of computer or its installation location, each of the above functional blocks may be realized by the hardware resources of a single computer or by combining hardware resources distributed across multiple computers.

[0026] The reference point detection unit 41 detects a reference point on the rotational orbit of a rotary conveyance unit that conveys the printing substrate 50 by rotation in the inkjet printing unit 11. Examples of the rotary conveyance unit for which the reference point is to be detected include the main conveyance rollers 112, first sub-conveyor rollers 113A, and second sub-conveyor rollers 113B, which are schematically shown in Fig. 1. The reference point detection unit 41, which detects a reference point on the circumference of the main conveyance rollers 112 and the like as the rotary conveyance unit, includes at least one of an encoder 411 and a proximity sensor 412.

[0027] The encoder 411 detects the rotational position of the main transport roller 112 and outputs a reference point detection signal when a reference point on the circumference of the main transport roller 112 reaches a predetermined rotational position. FIG. 2 schematically shows an example of how the encoder 411 detects a reference point on the circumference of the main transport roller 112. The encoder 411 may be an incremental type or an absolute type. In the case of an incremental type encoder 411 that outputs a Z-phase signal with each rotation of the main transport roller 112, as shown in FIG. 2, the encoder 411 outputs a Z-phase signal as a reference point detection signal when a reference point P on the circumference of the main transport roller 112 reaches the printing position of the first print nozzle 111A. In other words, in the illustrated state where the reference point P is on the straight line L connecting the center O of the main transport roller 112 and the tip (ink ejection end) of the first print nozzle 111A, the incremental encoder 411 is attached to the main transport roller 112 and / or the drive motor (not shown) that rotates it so that the detected mechanical angle (rotational angle) of the main transport roller 112 is "0 degrees" (or "360 degrees"), at which a Z-phase signal should be output.

[0028] When the main transport rollers 112 rotate clockwise from the illustrated state, the detected mechanical angle of the main transport rollers 112 counts up from "0 degrees" to "359 degrees" based on the A-phase and B-phase signals output by the incremental encoder 411. Then, when the main transport rollers 112 return to the illustrated state, the detected mechanical angle of the main transport rollers 112 is reset from "360 degrees" to "0 degrees" based on the Z-phase signal output as a reference point detection signal by the incremental encoder 411.

[0029] In the example of FIG. 2, the incremental encoder 411 outputs a Z-phase signal as a reference point detection signal in the illustrated state. However, various modifications are possible, such as the following. For example, the "0 degree" rotation position at which the incremental encoder 411 outputs a Z-phase signal as a reference point detection signal may be the position of reference point P', which is schematically indicated by a dotted line. This reference point P' is located before the printing location (the location of the aforementioned reference point P) of the first print nozzle 111A. As described below, the reference point detection signal triggers the start of inkjet printing by the print nozzles 111 (particularly the first print nozzle 111A, the frontmost one). However, there may be a non-negligible delay between the output timing of the reference point detection signal (Z-phase signal) by the reference point detector 41 (encoder 411) and the start timing of inkjet printing by the print nozzle 111. In such cases, the impact of the delay in the start of inkjet printing by the print nozzle 111 can be reduced by positioning the reference point P', at which the Z-phase signal should be output, before (counterclockwise from) the aforementioned reference point P.

[0030] Furthermore, the reference point detection signal output by the incremental encoder 411 is not limited to a Z-phase signal, but may also be an A-phase signal and / or a B-phase signal. For example, to reduce the effect of a delay in the start of inkjet printing by the print nozzle 111 as described above, the reference point detection signal is output before the reference point P is at "0 degrees" (or "360 degrees") as shown in the figure, for example, when the reference point P is at the rotational position P' (e.g., "345 degrees") as shown in the figure. Since the signal output by the incremental encoder 411 at this rotational position is an A-phase signal and / or a B-phase signal, these are used as reference point detection signals instead of a Z-phase signal to start inkjet printing by the print nozzle 111. Note that even if the encoder 411 is an absolute encoder, it can output a reference point detection signal when the reference point P (or P') on the circumference of the main transport roller 112, first sub-transport roller 113A, second sub-transport roller 113B, etc., reaches any rotational position, just like the incremental encoder 411 described above.

[0031] 2 schematically illustrates the reference point P (or P') detected by the encoder 411 serving as the reference point detector 41. However, even without such a mark, the encoder 411 can detect the mechanical angle of the main transport rollers 112 and output a Z-phase signal or the like as a reference point detection signal. On the other hand, when the reference point detector 41 is configured using a proximity sensor 412, it is preferable to provide a mark for the reference point P (or P') as shown, which can be detected by the proximity sensor 412, on the circumference of the main transport rollers 112 and the like. Furthermore, the rotary transport unit for which the reference point detector 41 detects the reference point is not limited to transport rollers such as the main transport rollers 112, the first sub-transport rollers 113A, and the second sub-transport rollers 113B. For example, the reference point P on the rotational orbit of any rotary transport unit that transports the printing substrate 50 by a rotationally driven endless track or ring-shaped belt can be detected by the reference point detector 41, such as the encoder 411 or the proximity sensor 412. Furthermore, a plurality of reference points P may be provided at regular intervals on the rotational path of the rotary conveyance section.

[0032] In response to the detection of reference point P by the reference point detector 41, the inkjet printing start unit 42 starts printing on the print substrate 50 using the print nozzle 111. In the example of FIG. 2, when reference point P reaches the illustrated "0 degree" rotation position, a reference point detection signal such as a Z-phase signal is output from the encoder 411, triggering the inkjet printing start unit 42 to cause the first print nozzle 111A (the foremost print nozzle) to start inkjet printing using the "0 degree" rotation position as the printing location. As described above, if there is a delay between the output timing of the reference point detection signal (such as a Z-phase signal) and the start timing of inkjet printing by the first print nozzle 111A, the reference point detector 41 can be caused to output a reference point detection signal (such as an A-phase signal and / or a B-phase signal) when reference point P reaches the illustrated rotation position P' (e.g., "345 degrees") in front of the first print nozzle 111A, causing the first print nozzle 111A to start inkjet printing simultaneously with the reference point P reaching the illustrated "0 degree" rotation position. Thereafter, when the reference point P reaches the rotational position of the second print nozzle 111B (for example, "25 degrees"), the inkjet printing start unit 42 causes the second print nozzle 111B to start inkjet printing, and when the reference point P reaches the rotational position of the third print nozzle 111C (for example, "50 degrees"), the inkjet printing start unit 42 causes the third print nozzle 111C to start inkjet printing.

[0033] The overprinting start position calculation unit 43 calculates the overprinting start position on the printing substrate 50 by the overprinting unit 12 in response to detection of the reference point P by the reference point detection unit 41. Here, the "overprinting start position" is substantially equal to the position on the printing substrate 50 at which the first printing nozzle 111A, the foremost nozzle, starts inkjet printing by the inkjet printing start unit 42. In the example of FIG. 2, the position on the printing substrate 50 indicated by the reference point P, which is at the "0 degree" rotation position at which the first printing nozzle 111A starts inkjet printing, is the overprinting start position S (which is also the inkjet printing start position S). The overprinting start position calculation unit 43 calculates the timing at which the overprinting start position S on the printing substrate 50 reaches the printing location by the plate cylinder 121 in the overprinting unit 12.

[0034] Note that if the horizontal scanning speed of the printing nozzle 111 described above is constant regardless of the vertical transport speed of the printing substrate 50, the primary pattern P1 printed by the printing nozzle 111 will be vertically squashed while the transport speed of the printing substrate 50 is not reaching the production speed. Because the secondary pattern P2 cannot be properly overprinted on such a primary pattern P1, the overprinting start position calculation unit 43 calculates the inkjet printing start position S and the overprinting start position S corresponding to the primary pattern P1 that will be printed first after the transport speed of the printing substrate 50 reaches the production speed. As will be described later, the reference point detection unit 41, such as the encoder 411, can detect that the transport speed of the printing substrate 50 has reached the production speed.

[0035] The overprinting start position calculation unit 43 calculates the overprinting start position S (or overprinting start timing) on ​​the printing substrate 50 based on the inkjet printing start position S in FIG. 2 by the inkjet printing start unit 42 (specifically, the first print nozzle 111A) and the distance d from the overprinting unit 12 (specifically, the plate cylinder 121), and the transport speed v of the printing substrate 50 by the transport rollers 23, etc. For example, if the transport speed v is constant, the overprinting start timing by the overprinting unit 12 is when a time d / v has elapsed since the first print nozzle 111A started inkjet printing at the inkjet printing start position S in FIG. 2. Here, the distance d between the inkjet printing unit 11 (first print nozzle 111A) and the overprinting unit 12 (plate cylinder 121) is a fixed value that is set in advance in the printing device 10.

[0036] Furthermore, as described above, the conveyance speed v of the printing substrate 50 may be calculated by the speed control unit 20 based on the detection interval of marks such as register marks by the mark sensor 21 and the known repeat length (the vertical distance between register marks at the production speed). However, this requires waiting until the register marks printed at the production speed in the inkjet printing unit 11 reach the mark sensor 21. Therefore, it is preferable to detect the conveyance speed v of the printing substrate 50 based on the detection interval (time) of the reference point P by the reference point detection unit 41, such as the encoder 411 or proximity sensor 412, provided in addition to the inkjet printing unit 11, and the length of the rotational path of the rotary conveyance unit (such as the main conveyance rollers 112) (in other words, the distance the reference point P travels until it is detected again by the reference point detection unit 41). The conveyance speed v detected by the reference point detection unit 41 based on the reference point P provided on the rotary conveyance unit in this way is highly accurate because it is not based on the repeat length (the vertical length of the primary pattern P1), which can vary depending on the conveyance speed of the rotary conveyance unit.

[0037] As described above, the transport speed v of the printing substrate 50 can be tracked immediately after the inkjet printing unit 11 (first print nozzle 111A) starts inkjet printing at the inkjet printing start position S. By quickly determining the transport speed v of the printing substrate 50, the transport distance of the printing substrate 50 from the inkjet printing start position S in FIG. 2 can be quickly calculated, thereby enabling the timing at which the overprinting start position S, where overprinting should begin, reaches the overprinting unit 12 to be determined with high accuracy. Thus, according to this embodiment, even if the transport speed v of the printing substrate 50 fluctuates, the overprinting start position S can be quickly determined and overprinting can be started appropriately. Therefore, waste of the printing substrate 50 (such as wasted paper) due to delays in determining the overprinting start position can be reduced. Note that the encoder 411, which can detect the rotation amount of the main transport roller 112, etc., can directly detect the transport distance of the printing substrate 50, so the overprinting start position may be determined without calculating the transport speed v.

[0038] The present invention has been described above based on the embodiments. Various modifications are possible to the combinations of the components and processes in the exemplary embodiments, and it will be obvious to those skilled in the art that such modifications are included within the scope of the present invention.

[0039] In the embodiment, a web of rolled paper is exemplified as the printing substrate 50, but the printing device 10 can print on any printing substrate. For example, the printing substrate may be a sheet made of any material, or the surface of a solid object of any shape, such as a container or a product.

[0040] The configuration, operation, and function of each device and method described in the embodiments can be realized by hardware resources, software resources, or a combination of hardware and software resources. Examples of hardware resources include processors, ROMs, RAMs, and various integrated circuits. Examples of software resources include operating systems, applications, and other programs. [Explanation of symbols]

[0041] 10 Printing device, 11 Inkjet printing unit, 12 Overprinting unit, 20 Speed ​​control unit, 30 Register control unit, 40 Printing control device, 41 Reference point detection unit, 42 Inkjet printing start unit, 43 Overprinting start position calculation unit, 50 Printing substrate, 111 Printing nozzle, 112 Main transport roller, 121 Plate cylinder, 411 Encoder, 412 Proximity sensor.

Claims

1. A print control device that controls a printing device that includes an inkjet printing unit that has print nozzles that eject ink onto a conveyed print substrate, and an overprinting unit that has a plate cylinder and an impression cylinder and performs overprinting on the print substrate at a stage subsequent to the inkjet printing unit, a reference point detection unit that detects a reference point on a rotational path of a rotary conveyance unit that conveys the printing material by rotation in the inkjet printing unit; an inkjet printing start unit that starts printing on the printing substrate by the print nozzle in response to detection of the reference point; an overprinting start position calculation unit that calculates an overprinting start position on the printing material by the overprinting unit in response to the detection of the reference point; Equipped with the overprinting start position calculation unit calculates the overprinting start position based on a distance between a print start position of the inkjet printing start unit and the overprinting unit and a conveyance speed of the printing medium; A print control device in which the conveying speed of the printing material is detected based on the detection interval of the reference point by the reference point detection unit and the length of the rotational orbit of the rotary conveying unit.

2. A printing control device as described in claim 1, which is provided between the inkjet printing unit and the reprinting unit and is equipped with a speed control unit that compares the current transport speed of the printed material with a target transport speed and controls the drive motor to reduce the difference.

3. the rotary conveying unit is a conveying roller provided in the inkjet printing unit, the reference point detection unit detects the reference point on the circumference of the conveyance roller; The print control device according to claim 1 or 2.

4. 4. The print control device according to claim 3, wherein the reference point detection unit is configured by an encoder that detects a rotational position of the transport roller, and outputs a reference point detection signal when the reference point reaches a predetermined rotational position.

5. the encoder is an incremental type that outputs a Z-phase signal for each rotation of the conveying roller, The reference point detection signal is the Z-phase signal. The print control device according to claim 4 .

6. The print control device according to claim 3 , wherein the transport roller is a main transport roller that transports the printing material at a position facing the print nozzle.

7. A printing control method for controlling a printing device including an inkjet printing unit having a printing nozzle that ejects ink onto a conveyed printing substrate, and an overprinting unit having a plate cylinder and an impression cylinder that performs overprinting on the printing substrate downstream of the inkjet printing unit, a reference point detection step of detecting a reference point on a rotational path of a rotary conveyance unit that conveys the printing material by rotation in the inkjet printing unit; an inkjet printing initiation step of starting printing on the printing substrate by the printing nozzle in response to detection of the reference point; an overprinting start position calculation step of calculating an overprinting start position on the printing material by the overprinting unit in response to the detection of the reference point; Equipped with the overprinting start position calculation step calculates the overprinting start position based on a distance between a printing start position in the inkjet printing start step and the overprinting unit and a conveying speed of the printing substrate; A printing control method in which the conveying speed of the printing medium is detected based on an interval between detections of the reference points in the reference point detection step and the length of the rotational path of the rotary conveying unit.

8. A printing control program for controlling a printing device including an inkjet printing unit having a printing nozzle that ejects ink onto a conveyed printing substrate, and an overprinting unit having a plate cylinder and an impression cylinder that performs overprinting on the printing substrate downstream of the inkjet printing unit, a reference point detection step of detecting a reference point on a rotational path of a rotary conveyance unit that conveys the printing material by rotation in the inkjet printing unit; an inkjet printing initiation step of starting printing on the printing substrate by the printing nozzle in response to detection of the reference point; an overprinting start position calculation step of calculating an overprinting start position on the printing material by the overprinting unit in response to the detection of the reference point; on the computer, the overprinting start position calculation step calculates the overprinting start position based on a distance between a printing start position in the inkjet printing start step and the overprinting unit and a conveying speed of the printing substrate; A printing control program in which the conveying speed of the printing material is detected based on the detection interval of the reference point in the reference point detection step and the length of the rotational orbit of the rotary conveying unit.

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