JP7494495B2 - Image forming apparatus, control method for image forming apparatus, and control program for image forming apparatus - Google Patents

Description

The present invention relates to an image forming apparatus, a control method for the image forming apparatus, and a control program for the image forming apparatus .

Conventionally, there are image forming devices that form (record) an image on a recording medium such as paper by ejecting ink from multiple nozzles provided in an inkjet head toward the recording medium. In addition, a technology has been proposed for forming an image in an image forming device by moving the inkjet head multiple times in the scanning direction, a so-called multi-pass image formation technique.

One example of a technique for forming an image using multiple passes is described in Patent Document 1. Patent Document 1 describes a technique for using an alternative nozzle in the overlapping area of multiple passes to complement a defective nozzle that has experienced a discharge defect such as a missing nozzle or a deflected discharge.

JP 2012-125957 A

In addition, image forming devices that combine image formation using the inkjet method and image formation using the screen method have been considered, but the technology described in Patent Document 1 has a fixed number of passes and does not take into account image formation using the screen method.

SUMMARY OF THE PRESENT DISCLOSURE In view of the above-mentioned problems in the prior art, an object of the present invention is to provide an image forming apparatus, a control method for an image forming apparatus, and a control program for an image forming apparatus, which take into consideration the image forming operation using a screen method.

In order to solve the above problems and achieve the object of the present invention, the image forming apparatus of the present invention includes a conveying unit, an inkjet unit, a screen printing unit, and a control unit. The conveying unit conveys a recording medium. The inkjet unit ejects ink from a plurality of nozzles provided in the inkjet head to form an image on the recording medium conveyed by the conveying unit. The screen printing unit is arranged alongside the inkjet unit along the conveying direction of the conveying unit, and forms an image on the recording medium by a screen method. The control unit sets the number of passes indicating the number of times an image is formed by moving the inkjet head in a scanning direction perpendicular to the conveying direction, based on the ink ejection state of the plurality of nozzles.

The method for controlling an image forming apparatus according to the present invention includes the following processes (1) to (3).
(1) A process of transporting the recording medium by a transport unit.
(2) A process in which ink is ejected from a plurality of nozzles provided in an inkjet head of an inkjet unit to form an image on a recording medium transported by a transport unit.
(3) A process in which an image is formed on a recording medium by a screen printing unit arranged alongside the inkjet unit along the conveying direction of the conveying unit.
In addition, the control method for the image forming apparatus sets the number of passes indicating the number of times an image is formed by moving the inkjet head in a scanning direction perpendicular to the transport direction, based on the ink ejection state of multiple nozzles before transporting the recording medium.

Further, a control program for an image forming apparatus according to the present invention causes a computer to execute the processes in the above-mentioned control method for an image forming apparatus.

According to the image forming apparatus, the control method for the image forming apparatus, and the control program for the image forming apparatus having the above-described configuration, the number of passes in the inkjet section can be set, and the image forming operation can be performed taking into account image formation using the screen method.

1 is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention; 2 is a block diagram showing a control system in the image forming apparatus according to the embodiment of the present invention. FIG. 2 is an explanatory diagram showing the positional relationship between an inkjet unit and an orthoscreen unit in an image forming apparatus according to an embodiment of the present invention; FIG. 5A and 5B are explanatory diagrams showing the operation during multi-pass image formation in the image forming apparatus according to the embodiment of the present invention; 4 is a flowchart showing an image forming operation in the image forming apparatus according to the embodiment of the present invention. 3A to 3C are explanatory diagrams showing an image forming operation in the image forming apparatus according to the embodiment of the present invention; The figures show the ink landing positions depending on the nozzle ejection state, with FIG. 7A showing a normal state, FIG. 7B showing a state where a nozzle has been deleted, FIG. 7C showing a state where ejection deflection has occurred, and FIG. 7D showing a state where the ejection force is weaker than a specified value. 8A and 8B show image forming operations when a nozzle ejection failure occurs in an image forming apparatus according to an embodiment of the present invention, with FIG. 8A showing image forming operations in one pass and FIG. 8B showing image forming operations in three passes.

Below, an embodiment of the present invention will be described with reference to Figs. 1 to 8. Note that the same reference numerals are used to designate the same components in each figure.

1. Example of the embodiment 1-1. Example of the configuration of the image forming apparatus First, an example of the configuration of an image forming apparatus according to an embodiment of the present invention (hereinafter, referred to as "this example") will be described with reference to FIG.
FIG. 1 is a schematic diagram showing the overall configuration of an image forming apparatus.

The image forming apparatus 1 shown in FIG. 1 is a combination of an inkjet type image forming apparatus and a screen type image forming apparatus. The image forming apparatus 1 has a conveying device 10, an inkjet section 30, an autoscreen section 40, a cleaning section 27, a gluing section 28, and a drying section 29. The image forming apparatus 1 also has a control section 50 (see FIG. 2) that controls the conveying device 10, the inkjet section 30, the autoscreen section 40, the cleaning section 27, the gluing section 28, and the drying section 29.

The conveying device 10 has a supply section 11, a conveying section 12, a peeling section 13, and a recovery section 14. The supply section 11 has a pay-out roller 16, a plurality of guide rollers 17, and a pressure roller 18. A recording medium P is wound around the pay-out roller 16. For example, a fabric is used as the recording medium P. The pay-out roller 16 is driven to rotate to pay out the wound recording medium P toward the guide roller 17.

The multiple guide rollers 17 are disposed between the delivery roller 16 and the pressure roller 18. The multiple guide rollers 17 apply tension to the recording medium P delivered from the delivery roller 16. This prevents the recording medium P from becoming wrinkled. The multiple guide rollers 17 also transport the recording medium P toward the pressure roller 18.

The pressure roller 18 presses the recording medium P conveyed from the guide roller 17 against the conveyor belt 21 of the conveyor section 12, which will be described later. The recording medium P is then placed on the surface of the conveyor belt 21, adhered thereto by the adhesive applied to the surface of the conveyor belt 21.

The conveying section 12 has a conveying belt 21, a driving roller 22, and a driven roller 23. The conveying belt 21 is formed in an endless shape. The conveying belt 21 is stretched between the driving roller 22 and the driven roller 23. The conveying belt 21 moves in a circle between the driving roller 22 and the driven roller 23 as the driving roller 22 is driven.

The inkjet unit 30 and the auto screen unit 40 are arranged side by side along the transport direction on the forward side of the transport belt 21 that transports the recording medium P. In this example, the inkjet unit 30 is arranged on the upstream side of the transport belt 21 in the transport direction, and the auto screen unit 40 is arranged on the downstream side of the transport direction. It is also possible to arrange the auto screen unit 40 on the upstream side of the transport direction and the inkjet unit 30 on the downstream side of the transport direction. Alternatively, the inkjet unit 30 may be arranged between the multiple screen printing units 42R, 42G, 42B, 42A, and 42O that make up the auto screen unit 40.

In addition, a cleaning unit 27 and a gluing unit 28 are arranged on the return path of the conveyor belt 21, opposite the outward path along which the recording medium P is conveyed. The cleaning unit 27 cleans stains such as colored glue and ink adhering to the surface of the conveyor belt 21. The gluing unit 28 applies glue to the surface of the conveyor belt 21. As a result, when the recording medium P is placed on the surface of the conveyor belt 21, the recording medium P adheres to the surface of the conveyor belt 21 with an appropriate strength. Note that the cleaning operation by the cleaning unit 27 and the gluing operation by the gluing unit 28 do not have to be performed every cycle.

Furthermore, a peeling unit 13 is disposed downstream of the autoscreen unit 40 on the conveyor belt 21 in the conveying direction. The peeling unit 13 is disposed away from the surface of the conveyor belt 21. The peeling unit 13 lifts up the recording medium P placed on the surface of the conveyor belt 21 and peels off the glued recording medium P from the conveyor belt 21. The peeling unit 13 then conveys the recording medium P downstream in the conveying direction.

A drying unit 29 is disposed downstream of the peeling unit 13 in the transport direction. The drying unit 29 dries the ink and color paste adhering to the recording medium P. A recovery unit 14 is disposed downstream of the drying unit 29 in the transport direction.

The recovery section 14 has a number of shake-off rollers 25 and a dolly 26. The shake-off rollers 25 fold the recording medium P that has been dried in the drying section 29 multiple times. The shake-off rollers 25 then transport the folded recording medium P toward the dolly 26, and store the recording medium P in the dolly 26.

The conveying device 10 also performs so-called intermittent conveying operations, in which the conveying drive unit 65 (described later) repeatedly feeds and pauses the recording medium P in accordance with the image forming operations of the inkjet unit 30 and the autoscreen unit 40.

The inkjet unit 30 has an inkjet head 32 that ejects ink, and a carriage 33 (see Figure 2) that movably supports the inkjet head 32.

In addition, the inkjet head 32 is provided for each of a number of colors, such as yellow (Y), magenta (M), cyan (C), and black (K). In addition, the inkjet head 32 has a tank for storing ink, a pipe through which the ink passes, a piezoelectric element, a nozzle from which the ink is ejected, etc.

The piezoelectric element is an actuator that applies pressure fluctuations to the ink in the nozzle 37 in order to eject the ink from the nozzle 37. The piezoelectric element is driven based on a voltage signal from the head drive unit 31 (see FIG. 2), which will be described later. Note that the actuator is not limited to the piezoelectric element, and may be, for example, an electric heating wire that heats the ink in the nozzle 37 to generate bubbles.

The nozzles 37 are provided on the surface of the inkjet head 32 that faces the surface of the conveyor belt 21 and the recording medium P. When the piezoelectric element is driven, ink is ejected from the nozzles 37.

The carriage 33 moves the inkjet head 32 in a direction (scanning direction) perpendicular to the transport direction of the recording medium P and perpendicular to the direction facing the recording medium P. The carriage 33 has, for example, a motor, two pulleys rotated by the motor, and a belt stretched between the two pulleys. The carriage 33 rotates the motor based on a drive signal output by a scan drive unit 34 (see FIG. 2), which will be described later, to move the inkjet head 32. The inkjet unit 30 ejects ink from nozzles 37 of the inkjet head 32 toward the recording medium P to form an image on the recording medium P.

The auto screen unit 40 has multiple screen printing units 42R, 42G, 42B, 42A, and 42O to apply color paste of a specific color to the recording medium P in a predetermined image pattern. The auto screen unit 40 forms an image according to each image pattern by applying color paste of each color to the recording medium P using the multiple screen printing units 42R, 42G, 42B, 42A, and 42O. For example, red, green, blue, gray, and gold color pastes are used as the screen printing units 42R, 42G, 42B, 42A, and 42O, respectively.

Since the multiple screen printing units 42R, 42G, 42B, 42A, 42O each have the same configuration, only the first screen printing unit 42R will be described here. The first screen printing unit 42R has a squeegee (spatula), a squeegee drive unit that moves the squeegee, a plate with holes formed with a predetermined image pattern, and colored paste of a specific color (e.g., red). The squeegee drive unit is driven in response to a drive signal from the screen drive unit 41, which will be described later, and the squeegee moves while applying pressure to the plate. As a result, the colored paste that passes through the holes in the plate adheres to the recording medium P, forming a predetermined image pattern of the specific color (red) on the recording medium P.

The length L of each screen printing unit 42R, 42G, 42B, 42A, 42O in the conveying direction is the same as the printing length L of the image formed on the recording medium P. The interval between each screen printing unit 42R, 42G, 42B, 42A, 42O is adjusted to the length L. The interval between the reference nozzle 37A (see FIG. 4) of the inkjet head 32 of the inkjet unit 30 and the first screen printing unit 42R is adjusted to an integer multiple of the printing length L, and is set to 2L in this example. The positional relationship between the inkjet unit 30 and the first screen printing unit 42R will be described in detail later.

The image forming device 1 also has a float detection sensor 15 located upstream of the inkjet unit 30 in the transport direction. The float detection sensor 15 detects whether the recording medium P has floated up from the transport belt 21. Information detected by the float detection sensor 15 is output to the control unit 50.

1-2. Example of Control System Configuration Next, the configuration of the control system of the image forming apparatus 1 will be described with reference to FIG.
FIG. 2 is a block diagram showing the configuration of a control system of the image forming apparatus 1. As shown in FIG.

As shown in FIG. 2, the image forming device 1 has a control unit 50 that controls the conveying device 10, the inkjet unit 30, the autoscreen unit 40, the cleaning unit 27, the gluing unit 28, and the drying unit 29. The image forming device 1 also has a first operation unit 52, a first display unit 53, a second operation unit 62, and a second display unit 63.

The control unit 50 has, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory) used as the CPU's working area, and a ROM (Read Only Memory) for storing programs executed by the CPU, etc.

The control unit 50 has an inkjet control unit 51 that controls the inkjet unit 30, and a screen control unit 61 that controls the autoscreen unit 40. The inkjet control unit 51 is connected to the inkjet unit 30, the first operation unit 52, and the first display unit 53 via a first system bus 55.

The first operation unit 52 accepts operation input from the user and outputs operation information to the inkjet control unit 51 in response to the operation input. As the first operation unit 52, for example, a touch panel superimposed on the display panel of the first display unit 53, various keys, etc. are used.

The first display unit 53 has a display panel such as an LCD (Liquid Crystal Display) or an EL (Electro Luminescence) display. The first display unit 53 displays various display information on the display panel based on the control of the inkjet control unit 51. Examples of display information include a status screen, a menu screen, and a setting screen related to inkjet image formation.

The inkjet unit 30 has a head driver 31, an inkjet head 32, a carriage 33, and a scan driver 34. Based on the control of the inkjet control unit 51, the head driver 31 outputs a voltage signal to the inkjet head 32 to deform the piezoelectric elements of the inkjet head 32 in a desired pattern. Based on the control of the inkjet control unit 51, the scan driver 34 outputs a drive signal to the carriage 33.

The screen control unit 61 is connected to the auto screen unit 40, the second operation unit 62, and the second display unit 63 via the second system bus 70. The second operation unit 62 accepts operation input from the user and outputs operation information to the screen control unit 61 in response to the operation input. As with the first operation unit 52, the second operation unit 62 may be a touch panel superimposed on the display panel of the second display unit 63, various keys, etc.

The second display unit 63 has a display panel such as an LCD (Liquid Crystal Display) or an EL (Electro Luminescence) display. The second display unit 63 displays various display information on the display panel based on the control of the screen control unit 61. Examples of display information include a status screen, a menu screen, and a setting screen related to inkjet image formation.

The autoscreen unit 40 has a screen drive unit 41 and screen printing units 42R, 42G, 42B, 42A, and 42O corresponding to each color. The screen drive unit 41 drives the squeegees provided in each screen printing unit 42R, 42G, 42B, 42A, and 42O based on the control of the screen control unit 61.

The inkjet control unit 51 and the screen control unit 61 are connected to each other so that they can communicate information, for example. The communication method between the inkjet control unit 51 and the screen control unit 61 is, for example, input/output signal line communication, serial communication, or a wired or wireless LAN (Local Area Network).

The image forming device 1 also has a transport drive unit 65, a drying drive unit 66, a cleaning drive unit 67, and a gluing drive unit 68. The transport drive unit 65, the drying drive unit 66, the cleaning drive unit 67, and the gluing drive unit 68 are connected to the control unit 50 via a third system bus 80.

The transport drive unit 65 outputs drive signals to each part of the transport device 10 under the control of the control unit 50 to operate each part. The drying drive unit 66 performs a predetermined operation to dry the ink and color paste on the recording medium P inside the drying unit 29 under the control of the control unit 50. Examples of the predetermined operation include, but are not limited to, a heat generation operation of a heating element such as a heater, or an air blowing operation by rotating a fan, or a combination of these.

The cleaning drive unit 67 operates the cleaning unit 27 based on the control of the control unit 50 to perform a cleaning operation. Examples of cleaning operations include an application operation to apply detergent to the conveyor belt 21 and a wiping operation to wipe off dirt adhering to the conveyor belt 21. In addition, when the operation of the cleaning unit 27 is not performed continuously, the cleaning drive unit 67 may temporarily separate the cleaning unit 27 from the conveyor belt 21. Based on the control of the control unit 50, the gluing drive unit 68 operates the gluing unit 28 to apply glue to adhere the recording medium P to the surface of the conveyor belt 21.

The conveying drive unit 65, the drying drive unit 66, the cleaning drive unit 67, and the gluing drive unit 68 may be controlled by the inkjet control unit 51 or the screen control unit 61.

The control unit 50 is also connected to, for example, an external information processing device, PC2, via a communication line. The control unit 50 receives job data sent from PC2 via the communication line. The control unit 50 then sends the received job data to the inkjet control unit 51 and the screen control unit 61.

In this embodiment, an example in which a personal computer is used as the external device has been described, but the present invention is not limited to this, and various other devices such as a facsimile machine can also be used as the external device.

1-3 Positional Relationship Between Inkjet Unit and Autoscreen Unit Next, a detailed positional relationship between the inkjet unit 30 and the autoscreen unit 40 in the image forming apparatus 1 having the above-described configuration will be described with reference to FIG.
Fig. 3 is an explanatory diagram showing the positional relationship between the inkjet unit 30 and the autoscreen unit 40. Fig. 3 also illustrates an example of forming an image Q1 in one scanning operation, that is, in one pass. In this example, one pass is set as the reference pass number.

As shown in FIG. 3, the inkjet head 32 extends parallel to the transport direction of the recording medium P. The inkjet head 32 has a plurality of nozzles 37 formed at a predetermined interval along the transport direction of the recording medium P. Of the plurality of nozzles 37, the nozzle 37 located at the lower end of the plate transport direction in the first screen printing unit 42R, i.e., at a position that is an integer multiple of the printing length L from the plate tip position X1 of the first screen printing unit 42R, is set as the reference nozzle 37A. In this example, the distance between the reference nozzle 37A and the plate tip position X1, which indicates the screen side reference point, is set to 3L.

The reference nozzle 37A is located at the downstream end of the print area W in the inkjet unit 30 in the transport direction, i.e., at the leading edge position W1 of the print area W. This print area W is obtained, for example, from job data. The leading edge position W1 indicates the image-side reference point. The inkjet head 32 uses nozzles 37L (used nozzles 37L) of the multiple nozzles 37 that are a length L from the reference nozzle 37A toward the upstream side in the transport direction. The transport drive unit 65 transports the transport belt 21 by the length L at a time.

This allows the leading edge position W1 of the printing area W on the recording medium P transported to the first screen printing unit 42R to be aligned with the leading edge position X1 of the plate on the first screen printing unit 42R.

The reference nozzle 37A is set to a nozzle 37 among the multiple nozzles 37 whose distance from the plate tip position X1 of the first screen printing unit 42R is an integer multiple of the printing length L, depending on the length of the printing length L. This allows the image tip position W1 to be aligned to the desired position when performing image formation processing in the inkjet unit 30, even if the length of the printing length L changes.

Next, the feed amount (conveyance amount) of the recording medium P in one pass during multi-pass image formation will be described with reference to FIG.
Fig. 4 is an explanatory diagram showing the operation during multiple passes, so-called multi-pass image formation. Fig. 4 also describes an example of forming image Q1 with three scanning operations, so-called three-pass image formation. Note that one pass can improve the work speed of the image formation process. In contrast, multi-pass can form a high-definition image and can prevent image defects even if nozzle discharge defects occur. The image formation operation during nozzle discharge defects will be described later.

Here, the use nozzles 37L are divided into a first use nozzle group 37L1, a second use nozzle group 37L2, and a third use nozzle group 37L3. The first use nozzle group 37L1 is located on the upstream side of the use nozzles 37L in the transport direction, and the third use nozzle group 37L3 is located on the downstream side of the use nozzles 37L in the transport direction. The second use nozzle group 37L2 is disposed between the first use nozzle group 37L1 and the third use nozzle group 37L3. The interval between the first use nozzle group 37L1, the second use nozzle group 37L2, and the third use nozzle group 37L3 is set to L/3.

First, as shown in FIG. 4A, the recording medium P is transported to a position L/3 away from the upstream end of the printing area W in the transport direction in the inkjet unit 30. Then, the inkjet unit 30 forms a first pass image on the recording medium P using the first nozzle group 37L1 among the nozzles 37L in use.

Next, as shown in FIG. 4B, the transport drive unit 65 transports the recording medium P by L/3. Then, the inkjet unit 30 forms an image in the second pass on the recording medium P using the first operating nozzle group 37L1 and the second operating nozzle group 37L2 of the operating nozzles 37L. At this time, the image formation area of the second operating nozzle group 37L2 overlaps with the image formation area of the first operating nozzle group 37L1 in the first pass.

Next, as shown in FIG. 4C, the transport drive unit 65 transports the recording medium P by L/3. Then, the inkjet unit 30 forms an image on the recording medium P in the third pass (final pass) using the first operating nozzle group 37L1, the second operating nozzle group 37L2, and the third operating nozzle group 37L3, i.e., all of the operating nozzles 37L. At this time, the image formation area of the second operating nozzle group 37L2 overlaps with the image formation area of the first operating nozzle group 37L1 in the second pass, and the image formation area of the third operating nozzle group 37L3 overlaps with the image formation area of the second operating nozzle group 37L2 in the second pass.

In the final pass, the leading edge position W1 of the print area W overlaps with the reference nozzle 37A in the transport direction. In other words, during multi-pass printing, the control unit 50 sets the feed amount so that the leading edge position W1 of the final pass overlaps with the reference nozzle 37A set during the first pass.

The recording medium P is then transported by L/3, and the first active nozzle group 37L1 forms the next image upstream of the current image Q1 in the transport direction. The second active nozzle group 37L2 and the third active nozzle group 37L3 then form the current image Q1. The recording medium P is then transported by L/3, and the first active nozzle group 37L1 and the second active nozzle group L2 form the next image, while the third active nozzle group 37L3 forms the current image Q1.

The first screen printing unit 42R performs screen printing every time the inkjet unit 30 performs the image formation process three times, in accordance with the number of passes of the inkjet unit 30.

This allows the leading edge position W1 of the printing area W on the recording medium P transported to the first screen printing unit 42R to be aligned with the leading edge position X1 of the plate on the first screen printing unit 42R. As a result, even if the image formation process in the inkjet unit 30 is one-pass or multi-pass, it is possible to prevent misalignment between the position of the inkjet image formed by the inkjet unit 30 and the position of the first screen image formed by the first screen printing unit 42R.

2. Operation of Image Forming Apparatus Next, an example of the operation of the image forming apparatus 1 having the above-described configuration will be described with reference to FIGS.
FIG. 5 is a flowchart showing the image forming operation.

As shown in FIG. 5, the control unit 50 obtains the printing length L of the printing area W where image formation is performed from the input job data (step S11). Next, the control unit 50 calculates the nozzles 37L to be used from among the multiple nozzles 37 based on the printing length L obtained in step S11 (step S12). In the process of step S12, the control unit 50 calculates the nozzles 37 of the multiple nozzles 37 that are the nozzles 37 that are the length of the printing length L from the reference nozzle 37A as the nozzles 37L to be used.

Next, the control unit 50 determines whether the number of passes in the inkjet unit 30 is to be set manually or automatically (step S13). The determination in step S13 may be made based on the input job data, or may be made based on information input to the first operation unit 52.

If the control unit 50 determines in the process of step S13 that manual setting is to be performed (manual setting in step S13), the control unit 50 causes the first display unit 53 to display a pass number setting screen. Then, the user sets the pass number via the first operation unit 52 (step S14). When the pass number is set in the process of step S14, the control unit 50 proceeds to the process of step S16, which will be described later.

In addition, if the control unit 50 determines in the process of step S13 that automatic setting is to be performed (automatic setting in step S13), the control unit 50 sets the number of passes based on the ejection state of the nozzle 37L in use of the inkjet head 32 (step S15). When the number of passes is set in the process of step S15, the control unit 50 proceeds to the process of step S16.

The ink ejection state refers to a nozzle defect where ink is not ejected from the nozzle 37, an ejection deflection where the ejected ink is deflected from the predetermined landing position, etc., and the job data input to the control unit 50. The nozzle ejection state will be described later. The job data also refers to a normal printing mode or a high-definition mode that indicates the image quality of the image Q1 to be formed. For example, in the normal printing mode, the number of passes is set to one pass, and in the high-definition mode, the number of passes is set to multiple passes such as three passes or four passes.

In the process of step S16, the control unit 50 calculates the feed amount of the recording medium P based on the set number of passes and the print length L or the number of nozzles 37L used. Here, if the number of passes is n and the print length is L, the feed amount T is set to L/n.

Next, the control unit 50 creates a print mask based on the number of passes and the nozzles 37L used (step S17). The print mask is data that specifies the positions and amount of ink ejected from the nozzles 37L used for the image to be formed.

Next, the control unit 50 sets the number of nozzles 37 to be used in each pass and the position of the recording medium P relative to the inkjet head 32 based on the number of passes, the feed amount, and the print mask (step S18).

Next, the inkjet control unit 51 controls the head drive unit 31 and the scan drive unit under the conditions set in the above-mentioned process, and starts image formation by the inkjet unit 30. The screen control unit 61 also controls the screen drive unit 41 in accordance with the image formation conditions of the inkjet unit 30, and starts printing by the autoscreen unit 40 (step S19).

The control unit 50 then controls the transport drive unit 65 to start transporting the recording medium P at the feed amount set in step S16 (step S20).

By repeating the processes of steps S19 and S20, as shown in FIG. 6, first, an image Q1 (inkjet image) is formed in the printing area W of the recording medium P by the inkjet unit 30 arranged at the most upstream side in the transport direction. Next, the recording medium P is transported to the first screen printing unit 42R. Then, an image S1 (first screen image) indicated by "A" is formed in the printing area W of the recording medium P by the first screen printing unit 42R.

Next, the recording medium P is transported to the second screen printing unit 42G. Then, the second screen printing unit 42G forms an image S2 (second screen image) indicated by "B" in the printing area W of the recording medium P. Furthermore, the recording medium P is transported to the third screen printing unit 42B, and the third screen printing unit 42B forms an image S3 (third screen image) indicated by "C" in the printing area W of the recording medium P.

Next, the recording medium P is transported to the fourth screen printing unit 42A, which applies a solid coat of color paste to the entire printing area W of the recording medium P. The recording medium P is then transported to the fifth screen printing unit 42O (see FIG. 1), which is not shown in FIG. 6 and is located at the most downstream position in the transport direction, and a predetermined image is formed in the printing area W of the recording medium P by the fifth screen printing unit 42O.

As a result, the inkjet image Q1, the first screen image S1, the second screen image S2, the third screen image S3 and the solid screen image are superimposed on the printing area W of the recording medium P.

3. Nozzle Ejection States Next, the nozzle ejection states and the control operation of the inkjet unit 30 in response to the nozzle ejection states will be described with reference to FIGS.
Figures 7A to 7D are explanatory diagrams showing the ink landing positions during ink ejection, with Figure 7A showing the normal state, Figure 7B showing a state where a nozzle is missing, Figure 7C showing a state where ejection deflection has occurred, and Figure 7D showing a state where the ejection force is weaker than a specified value.

Under normal conditions, ink F1 lands at a predetermined position, as shown in FIG. 7A. In contrast, if a nozzle is missing, ink F1 does not land at the predetermined position, as shown in FIG. 7B. Furthermore, if nozzle 37 is deflected, ink F1 lands at a position different from the predetermined position, as shown in FIG. 7C.

Furthermore, if the ejection force from the nozzle 37 weakens, as shown in FIG. 7D, the ink F1 lands at a position other than the predetermined position along the movement direction of the carriage 33. When the image detection unit detects the states shown in FIG. 7B to FIG. 7D, the control unit 50 determines that an ejection defect has occurred in the nozzle 37.

Figures 8A and 8B are explanatory diagrams showing the image formation operation when a discharge defect occurs in nozzle 37. Figure 8A shows the image formation operation in one pass, and Figure 8B shows the image formation operation in three passes.

As shown in FIG. 8A, if a defective nozzle 37G, such as a missing nozzle, occurs among the nozzles 37L in use, a white streak K1 occurs in the formed image Q1 along the scanning direction of the inkjet head 32. Therefore, when the control unit 50 determines that a defective nozzle 37G exists among the nozzles 37L in use, it sets the number of passes of the inkjet unit 30 to multi-pass in the process of step S15 shown in FIG. 5.

As shown in FIG. 8B, in a three-pass image formation operation, the control unit 50 sets, among the nozzles 37 used in the first pass, the nozzles that are located in positions corresponding to the defective nozzles 37G in image Q1 in the second and third passes as complementary nozzles 37C. Also, among the nozzles 37 used in the second pass, the nozzles that are located in positions corresponding to the defective nozzles 37G in image Q1 in the first and third passes as complementary nozzles 37C. Similarly, among the nozzles 37 used in the third pass, the nozzles that are located in positions corresponding to the defective nozzles 37G in image Q1 in the first and second passes are set as complementary nozzles 37C.

The control unit 50 then modifies the print mask to increase the amount of ink ejected from the complementary nozzle 37C. In this way, by setting the number of passes and the complementary nozzle 37C according to the ejection state of the used nozzle 37L, image defects such as white streaks K1 caused by a defective nozzle G can be complemented K2 by the complementary nozzle 37C, as shown in FIG. 8B.

Furthermore, by setting the reference nozzle 37A and the number of passes, the complementary nozzle 37C can be easily set. Also, by setting the reference nozzle 37A and the nozzle in use 37L in advance and setting the feed amount based on this reference nozzle 37A, it is possible to prevent the leading edge position W1 of the printing area W from shifting between the inkjet unit 30 and the autoscreen unit 40 even if the number of passes changes.

Furthermore, although the nozzle ejection state has been described as being defective in the nozzle 37, this is not limiting. As the nozzle ejection state, ink bleeding, color breakup, etc. caused by differences in the material of the recording medium P may also be taken into consideration. The control unit 50 may set the number of passes taking into consideration image defects caused by bleeding, color breakup, etc. as the ejection state.

The present invention is not limited to the embodiment described above and shown in the drawings, and various modifications are possible without departing from the spirit of the invention described in the claims.

In the above embodiment, the plate leading edge position X1 is used as the screen side reference point, and the leading edge position W1 is used as the image side reference point, but the present invention is not limited to this. For example, the upstream end of the plate in the conveying direction, i.e., the rear end position of the plate, may be used as the screen side reference point, and the upstream end of the image printing area, i.e., the rear end position, may be used as the image side reference point. This image side reference point may be any point that overlaps with the plate side reference point when the recording medium is conveyed to the screen printing section. In addition, the reference nozzle is a nozzle among the multiple nozzles that is located at a distance from the plate rear end position that is an integer multiple of the printing length.

When an image is formed on the recording medium using the reference number of passes, the trailing edge of the print area is transported to match the position of the reference nozzle. Also, when an image is formed using multiple passes, the trailing edge of the print area overlaps with the reference nozzle during the final pass.

The image side reference point needs to be a point that overlaps with the plate side reference point when the recording medium is transported to the screen printing section. The reference nozzle is set based on the plate side reference point and the printing length, and overlaps with the image side reference point when the recording medium is transported to the inkjet section during the reference number of passes. In addition, during multi-pass printing, the reference nozzle and image side reference point overlap during the final pass.

In addition, the reference number of paths is not limited to "1", but may be set to 2 or more paths.

Furthermore, although an example has been described in which the length of the portion of the inkjet head 32 where the nozzle 37 is formed is longer than the printing length L, this is not limiting. The length of the inkjet head 32 may be shorter than the printing length L. For example, if the length of the nozzle 37L used in the inkjet head 32 is 1/2 the printing length L, the feed amount during one pass is set to L/2, and the feed amount during three passes is set to L/6.

In addition, in the above-mentioned embodiment, an example was described in which paper was used as the recording medium, but this is not limited to this, and various other recording media such as fabric, plastic film, glass plate, and the like can also be used as the recording medium.

Furthermore, the above-mentioned components, functions, processing units, etc. may be realized in part or in whole in hardware, for example by designing an integrated circuit. Further, the above-mentioned components, functions, etc. may be realized in software by a processor interpreting and executing a program that realizes each function. Information on the programs, tables, files, etc. that realize each function can be stored in a recording device such as a memory, hard disk, or SSD (Solid State Drive), or on a recording medium such as an IC card, SD card, or DVD.

1...image forming apparatus, 10...conveying device, 11...supply section, 12...conveying section, 13...peeling section, 14...recovery section, 15...floating detection sensor, 16...feed-out roller, 17...guide roller, 18...pressure roller, 21...conveying belt, 22...driving roller, 23...driven roller, 27...cleaning section, 28...gluing section, 29...drying section, 30...inkjet section, 31...head driving section, 32...inkjet head, 33...carriage, 34...scanning driving section, 37...nozzle, 37A...reference nozzle, 37C...complementary nozzle, 37G...faulty nozzle, 37L...used nozzle, 37L1...first used nozzle group, 37L2...second used nozzle group, 37L3...third used nozzle group, 40...autoscreen section, 41...screen driving section, 42R, 42G, 42B, 42A, 42O...screen printing unit, 50...control unit, 51...inkjet control unit, 61...screen control unit, 65...transport drive unit, 66...drying drive unit, 67...cleaning drive unit, 68...gluing drive unit

Claims (23)

A conveying unit that conveys the recording medium;
an inkjet unit that ejects ink from nozzles provided in an inkjet head and forms an image on the recording medium transported by the transport unit;
a screen printing unit arranged next to the inkjet unit along a conveying direction of the conveying unit and forming an image on the recording medium by a screen printing method;
a control unit that sets nozzles to be used based on a printing length in the screen printing unit, and controls an image forming operation in the inkjet unit based on a discharge state of the nozzles to be used;
An image forming apparatus comprising: The image forming apparatus according to claim 1 , wherein the ink ejection state is a nozzle defect where ink is not ejected from the nozzle, an ejection deflection where the ejected ink is deflected from a predetermined landing position, or job data input to the control unit. The image forming operation controlled by the control unit is a setting of a pass number indicating the number of times an image is formed by moving the inkjet head in a scanning direction perpendicular to the transport direction.
The image forming apparatus according to claim 1 . The image forming operation controlled by the control unit is the control of the feeding operation of the recording medium.
The image forming apparatus according to claim 3 . A conveying unit that conveys the recording medium;
an inkjet unit that ejects ink from a plurality of nozzles provided in an inkjet head and forms an image on the recording medium transported by the transport unit;
a screen printing unit arranged next to the inkjet unit along a conveying direction of the conveying unit and forming an image on the recording medium by a screen printing method;
a control unit that sets a number of passes indicating the number of times an image is formed by moving the inkjet head in a scanning direction perpendicular to the transport direction, based on an ink ejection state of the plurality of nozzles; and
Equipped with
The ink ejection state is a nozzle defect where ink is not ejected from the nozzle, an ejection deflection where the ejected ink is deflected from a predetermined landing position, or job data input to the control unit,
an image reference point of an image to be formed on the recording medium overlaps with a plate side reference point in the screen printing unit when the recording medium is transported to the screen printing unit;
a nozzle that overlaps with the image reference point when the recording medium is transported to the inkjet unit among the plurality of nozzles during a preset reference pass number is set as a reference nozzle;
an interval from the reference nozzle to the plate-side reference point is set to an integral multiple of a printing length of a printing area acquired from the job data. the conveying unit conveys the recording medium intermittently by repeatedly performing a feeding operation and a temporary stop;
The image forming apparatus according to claim 5 , wherein the control unit calculates a feed amount of the recording medium per feed based on the set number of passes and the set printing length. The image forming apparatus according to claim 6 , wherein, when the number of passes is set to a plurality of passes, the control unit calculates the feed amount such that the image reference point overlaps the reference nozzle in a final pass. The image forming apparatus according to claim 4 , wherein the control unit sets the number of nozzles to be used in each pass among the active nozzles, based on the set number of passes and the feed amount of the recording medium. The image forming apparatus according to claim 3 , wherein the control unit acquires the ejection state, and when it determines that a defective nozzle that is defective in ejection is present among the active nozzles, sets the number of passes to a plurality of times. The image forming apparatus according to claim 9 , wherein the control unit sets a complementary nozzle that complements the defective nozzle among the nozzles used in each pass. The image forming apparatus according to claim 5 , wherein the reference number of passes is one. A process of conveying the recording medium by a conveying unit;
A process of ejecting ink from nozzles provided in an inkjet head of an inkjet unit to form an image on the recording medium transported by the transport unit;
forming an image on the recording medium by a screen printing unit arranged next to the inkjet unit along the conveying direction of the conveying unit,
The control unit sets the nozzles to be used based on the printing length in the screen printing unit, and performs processing to control the image forming operation in the inkjet unit based on the ejection state of the nozzles to be used.
A method for controlling an image forming apparatus. The ink ejection state is a nozzle defect where ink is not ejected from the nozzle, an ejection deflection where the ejected ink is deflected from a predetermined landing position, or job data input to the control unit.
The method for controlling the image forming apparatus according to claim 12. The image forming operation controlled by the control unit is a setting of a pass number indicating the number of times an image is formed by moving the inkjet head in a scanning direction perpendicular to the transport direction.
The method for controlling the image forming apparatus according to claim 12. The image forming operation controlled by the control unit is the control of the feeding operation of the recording medium.
The method for controlling the image forming apparatus according to claim 14. A process of conveying the recording medium by a conveying unit;
A process of ejecting ink from a plurality of nozzles provided in an inkjet head of an inkjet unit to form an image on the recording medium transported by the transport unit;
forming an image on the recording medium by a screen printing unit arranged next to the inkjet unit along a conveying direction of the conveying unit,
the control unit sets a number of passes indicating the number of times an image is formed by moving the inkjet head in a scanning direction perpendicular to the transport direction based on a discharge state of ink from the plurality of nozzles;
The ink ejection state is a nozzle defect where ink is not ejected from the nozzle, an ejection deflection where the ejected ink is deflected from a predetermined landing position, or job data input to the control unit,
an image reference point of an image to be formed on the recording medium overlaps with a plate side reference point in the screen printing unit when the recording medium is transported to the screen printing unit;
a nozzle that overlaps with the image reference point when the recording medium is transported to the inkjet unit among the plurality of nozzles during a preset reference pass number is set as a reference nozzle;
The length of the interval from the reference nozzle to the plate side reference point is set to an integral multiple of the printing length of the printing area acquired from the job data.
A method for controlling an image forming apparatus. the conveying unit conveys the recording medium intermittently by repeatedly performing a feeding operation and a temporary stop;
The control unit calculates the amount of feeding of the recording medium in one pass based on the set number of passes and the set printing length.
The method for controlling the image forming apparatus according to claim 16. When the number of passes is set to a plurality of passes, the control unit calculates the feed amount so that the image reference point overlaps the reference nozzle in the final pass.
The method for controlling the image forming apparatus according to claim 17. The control unit sets the number of nozzles to be used in each pass among the nozzles to be used, based on the set number of passes and the feed amount of the recording medium.
The method for controlling the image forming apparatus according to claim 15. The control unit acquires the ejection state, and when it determines that the nozzles in use are defective nozzles that are defective in ejection, sets the number of passes to a plurality of times.
The method for controlling the image forming apparatus according to claim 14. The control unit sets a complementary nozzle that complements the defective nozzle among the nozzles used in each pass.
The method for controlling an image forming apparatus according to claim 20. The number of reference passes is one.
The method for controlling the image forming apparatus according to claim 16. A method for controlling an image forming apparatus according to any one of claims 12 to 22, comprising the steps of:
A control program for an image forming apparatus.

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