JP7064837B2 - Inkjet printing equipment and transport equipment - Google Patents

Description

The present invention relates to an inkjet printing device and a transport device .

A line-type inkjet printing apparatus is known that prints by ejecting ink from an inkjet head to a print medium while transporting the print medium by a transport unit having a transport belt or the like (see, for example, Patent Document 1).

In an inkjet printing device, when ink is ejected from an inkjet head, ink mist in which the ink is atomized is generated. Ink mist may adhere to the inkjet head and its surrounding members. In the above-mentioned line-type inkjet printing apparatus, the ink mist adhering to the inkjet head or the like aggregates into a lump of ink due to the influence of the air flow generated by the transport of the print medium, and the ink drops off to the printed matter or the transport. There is a risk of soiling the part.

By the way, in the above-mentioned line type inkjet printing apparatus, when the next print job has been received at the end of printing based on the print job and the preparation of the image data for printing based on the print job is completed. The transfer and printing of the print medium are continued as they are.

On the other hand, even if the next print job has been received, the image data for printing based on the print job may not be prepared and printing based on the print job may not be performed immediately. In this case, if the transport unit is stopped until the preparation of the image data is completed, the air flow due to the operation of the transport unit is stopped. It is possible to prevent the ink from falling off.

Japanese Unexamined Patent Publication No. 2015-131451

However, once the operation of the transport unit is stopped, it takes a certain amount of time to start the transport unit and restart the transport of the print medium. Therefore, the start of printing based on the next print job is delayed, which causes a decrease in the productivity of the printed matter.

The present invention has been made in view of the above, and an object of the present invention is to provide an inkjet printing apparatus and a conveying apparatus capable of reducing dripping of ink on a printed matter or a conveying portion while suppressing a decrease in productivity of the printed matter.

In order to achieve the above object, the inkjet printing apparatus of the present invention includes a transport unit that transports a print medium while holding it on a transport surface, an inkjet head that ejects ink to the print medium conveyed by the transport unit, and the like. While controlling the transport unit, when a print job is received, the print job is expanded to generate image data for printing by the inkjet head, and ink is ejected from the inkjet head to the print medium based on the generated image data. A control unit that executes printing based on the print job is provided, and the control unit has received the next print job at the end of printing based on the print job, and prints based on the next print job. When the preparation of the image data for starting is not completed, the transport unit is controlled to perform low-speed driving in which the driving speed is lower than that at the time of printing until the preparation of the image data is completed. It is a feature.

According to the present invention, it is possible to reduce the amount of ink dripping on the printed matter or the conveying portion while suppressing the decrease in the productivity of the printed matter.

It is a schematic block diagram of the inkjet printing apparatus which concerns on 1st Embodiment. It is a top view of the belt platen part and the printing part of the inkjet printing apparatus shown in FIG. 1. It is a control block diagram of the inkjet printing apparatus shown in FIG. 1. It is a flowchart for demonstrating operation of the inkjet printing apparatus shown in FIG. It is a figure for demonstrating the process that ink drops. It is explanatory drawing of the airflow in 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or equivalent parts and components are designated by the same or equivalent reference numerals throughout the drawings.

The embodiments shown below exemplify an apparatus or the like for embodying the technical idea of the present invention, and the technical idea of the present invention includes the material, shape, structure, arrangement, etc. of each component. Is not specified as the following. The technical idea of the present invention can be modified in various ways within the scope of claims.

[First Embodiment]
FIG. 1 is a schematic configuration diagram of an inkjet printing apparatus according to a first embodiment of the present invention. FIG. 2 is a plan view of a belt platen portion and a printing portion of the inkjet printing apparatus shown in FIG. FIG. 3 is a control block diagram of the inkjet printing apparatus shown in FIG. In the following description, the direction orthogonal to the paper surface of FIG. 1 is defined as the front-back direction. Further, the vertical and horizontal directions of the paper surface in FIG. 1 are defined as the vertical and horizontal directions.

As shown in FIGS. 1 and 3, the inkjet printing apparatus 1 according to the first embodiment includes a paper feeding unit 2, a transport unit 3, a printing unit 4, and a control unit 5.

The paper feed unit 2 feeds the paper P to the transport unit 3. The paper feed unit 2 includes a paper feed table 11, a paper feed roller 12, a paper feed motor 13, a resist roller 14, and a resist motor 15.

The paper feed tray 11 is loaded with paper P, which is a print medium.

The paper feed roller 12 picks up the paper P loaded on the paper feed table 11 one by one and conveys it toward the resist roller 14.

The paper feed motor 13 drives the paper feed roller 12.

The resist roller 14 temporarily stops the paper P conveyed by the paper feed roller 12, and then conveys the paper P toward the transfer unit 3.

The resist motor 15 drives the resist roller 14.

The transport unit 3 transports the paper P fed from the paper feed unit 2. The transport unit 3 includes a transport belt 21, a drive roller 22, driven rollers 23 to 25, a transport motor 26, and a suction section 27.

The transport belt 21 attracts and holds the paper P transported by the resist roller 14 and transports the paper P. The transport belt 21 is an annular belt that is hung on the drive roller 22 and the driven rollers 23 to 25. As shown in FIG. 2, the transport belt 21 is formed with a large number of suction holes 21a which are through holes for air suction. The transport belt 21 sucks and holds the paper P on the transport surface 21b by the suction force generated in the suction hole 21a by the drive of the suction portion 27. The transport surface 21b is the upper surface of the transport belt 21 that is horizontal between the drive roller 22 and the driven roller 23. The transport belt 21 rotates (endlessly moves) in the clockwise direction in FIG. 1 to transport the suction-held paper P in the transport direction (secondary scanning direction) from left to right.

The drive roller 22 rotates the transport belt 21 in the clockwise direction in FIG.

The driven rollers 23 to 25 support the transport belt 21 together with the driving rollers 22. The driven rollers 23 to 25 are driven and rotated by the rotating conveyor belt 21. The driven roller 23 is at the same height as the drive roller 22 and is arranged on the left side of the drive roller 22. The driven rollers 24 and 25 are arranged below the drive roller 22 and the driven roller 23 at the same height so as to be separated from each other in the left-right direction.

The transfer motor 26 rotates and drives the drive roller 22.

The suction unit 27 creates a downward air flow. As a result, the suction unit 27 sucks air through the suction hole 21a of the transport belt 21 to generate a negative pressure in the suction hole 21a, and sucks and holds the paper P on the transport surface 21b of the transport belt 21. The suction portion 27 is arranged below the portion of the transport belt 21 that forms the transport surface 21b.

The suction unit 27 includes an upstream suction unit 28 and a downstream suction unit 29, respectively, for sucking air through the suction holes 21a. The upstream suction unit 28 and the downstream suction unit 29 each have at least one fan that produces a downward air flow. The upstream side suction portion 28 is arranged below the upstream portion of the transport surface 21b in the transport direction of the paper P. The downstream suction portion 29 is arranged below the downstream portion of the transport surface 21b. That is, the upstream suction section 28 and the downstream suction section 29 are arranged in parallel in the transport direction (left-right direction) of the paper P by the transport section 3, and the downstream suction section 29 is located on the downstream side of the upstream suction section 28. Is located in.

The printing unit 4 prints an image on the paper P conveyed by the conveying unit 3. The printing unit 4 is arranged above the transport unit 3. The printing unit 4 includes inkjet heads 31C, 31K, 31M, 31Y. In addition, the subscripts of the alphabet in the codes of the inkjet heads 31C, 31K, 31M, and 31Y may be omitted and collectively described.

The inkjet head 31 ejects ink onto the paper P conveyed by the conveying belt 21 and prints an image. The inkjet heads 31C, 31K, 31M, and 31Y are arranged in parallel in the left-right direction above the transport surface 21b of the transport belt 21. The inkjet heads 31C, 31K, 31M, and 31Y eject cyan (C), black (K), magenta (M), and yellow (Y) inks, respectively. The inkjet heads 31C, 31K, 31M, and 31Y each have six head modules 32, as shown in FIG.

In each inkjet head 31, the six head modules 32 are staggered along the main scanning direction (front-back direction). The head module 32 has a plurality of nozzles (not shown) arranged along the main scanning direction, and ejects ink from the nozzles. The nozzle is open on the nozzle surface 32a, which is the lower surface of the head module 32.

The head module 32 is a multi-drop system capable of ejecting a plurality of ink droplets from one nozzle to one pixel, and performs gradation printing in which the density is expressed by the number of ink droplets (the number of drops).

The control unit 5 controls the operation of each unit of the inkjet printing apparatus 1. The control unit 5 includes a CPU, RAM, ROM, a hard disk, and the like.

When the control unit 5 receives a print job from an external device such as a personal computer, the control unit 5 executes printing based on the print job. Specifically, the control unit 5 develops an image of a print job and generates image data for printing by the inkjet head 31. Then, the control unit 5 transfers the paper P by the transport unit 3, and ejects ink from the inkjet head 31 to the paper P based on the generated image data to print the image.

When the control unit 5 has received the next print job at the end of printing based on the print job and the preparation of the image data for starting the printing based on the next print job is not completed, the control unit 5 is concerned. Until the preparation of the image data is completed, the transport unit 3 is controlled so as to perform low-speed driving in which the driving speed is lower than that at the time of printing.

Next, the operation of the inkjet printing apparatus 1 will be described with reference to the flowchart of FIG.

In step S1 of FIG. 5, the control unit 5 receives a PDL (Page Description Language) format print job transmitted from an external device in a standby state in which the inkjet printing device 1 is not operating.

Next, in step S2, the control unit 5 starts a process of generating image data for printing by the inkjet heads 31C, 31K, 31M, 31Y from the print job. The image data for printing is drop data of each ink color of cyan (C), black (K), magenta (M), and yellow (Y). The drop data is data indicating the number of ink drops (the number of droplets) for each pixel.

The process of generating drop data, which is image data for printing, from a print job is performed as follows. First, the control unit 5 develops an image of a print job in PDL format and generates image data in RGB format. Next, the control unit 5 color-converts the RGB format image data into the CMYK format image data. Then, the control unit 5 performs halftone processing on the image data in CMYK format to generate drop data for each ink color. As the halftone processing, error diffusion processing and dither mask processing can be applied.

Further, in step S2, the control unit 5 starts driving the transport unit 3. Specifically, the control unit 5 starts driving the transfer motor 26 and the suction unit 27.

After the drive of the transfer motor 26 is started, the control unit 5 receives the print transfer speed when the moving speed of the transfer belt 21 that moves (rotates) endlessly reaches a predetermined print transfer speed which is the transfer speed at the time of printing by the inkjet head 31. The transport motor 26 is controlled so as to maintain the above speed. Here, when the paper P is held and transported on the transport surface 21b, the moving speed of the transport belt 21 becomes the transport speed of the paper P. In the inkjet printing apparatus 1, the standard drive is the drive of the transfer unit 3 performed by setting the transfer speed of the paper P (moving speed of the transfer belt 21) to the print transfer speed.

At the time of standard drive of the transport unit 3, the control unit 5 is set to suck the upstream suction unit 28 and the downstream suction unit 29 of the suction unit 27 so that the air volume thereof attracts the paper P to the transport surface 21b at the time of printing. Drive to the standard air volume.

After the drive of the transport unit 3 is started, in step S3, the control unit 5 determines whether or not the preparation (generation) of the image data (drop data) for starting printing based on the print job received in step S1 is completed. to decide. When it is determined that the preparation of the image data is not completed (step S3: NO), the control unit 5 repeats step S3.

When it is determined that the preparation of the image data is completed (step S3: YES), in step S4, the control unit 5 starts feeding and printing.

Specifically, the control unit 5 controls the paper feeding unit 2 to sequentially feed the paper P for the number of printed sheets to the conveying unit 3. The fed paper P is sucked and held on the transport surface 21b of the transport belt 21 in the transport unit 3 and transported. The control unit 5 controls the inkjet heads 31C, 31K, 31M, and 31Y based on the image data to eject ink onto the conveyed paper P to print an image. The printed paper is conveyed from the transport unit 3 to a paper discharge unit (not shown) and discharged.

After the start of paper feeding and printing, in step S5, the control unit 5 determines whether or not printing by the inkjet head 31 based on the print job is completed. If it is determined that printing has not been completed (step S5: NO), the control unit 5 repeats step S5.

When it is determined that printing is completed (step S5: YES), in step S6, the control unit 5 determines whether or not the next print job has been received.

Here, if the next print job is received before the printing based on the print job is completed, the control unit 5 starts a process of generating image data for printing from the next print job. When the next print job is received, if the process of generating image data for printing from the previous print job is in progress, the process of generating image data for printing from the next print job is performed after the process is completed. Start.

When it is determined that the next print job has been received (step S6: YES), in step S7, the control unit 5 has completed the preparation of the image data for starting printing based on the next print job. Judge whether or not.

When it is determined that the preparation of the image data is completed (step S7: YES), in step S8, the control unit 5 continues to start paper feeding and printing based on the next print job, so that the paper feeding unit 2 and printing are started. The unit 4 is controlled. At this time, the control unit 5 continues the standard drive of the transport unit 3. After step S8, the control unit 5 returns to the process of step S5.

If it is determined in step S7 that the preparation of the image data is not completed (step S7: NO), in step S9, the control unit 5 shifts the transport unit 3 to low-speed drive. Here, the low-speed drive of the transport unit 3 is a drive in which the drive speed is lower than the above-mentioned standard drive performed at the time of printing. Further, when the transport unit 3 is driven at a low speed, the air volume of the upstream suction unit 28 and the downstream suction unit 29 of the suction unit 27 is set to a predetermined weak air volume, which is smaller than the standard air volume.

Specifically, the control unit 5 controls the transport motor 26 so as to switch the moving speed of the transport belt 21 from the print transport speed to a predetermined low speed drive speed lower than that. At the same time, the control unit 5 switches the air volume of the upstream suction unit 28 and the downstream suction unit 29 of the suction unit 27 from the standard air volume to the weak air volume.

Next, in step S10, the control unit 5 determines whether or not the preparation of the image data for starting printing based on the next print job is completed. When it is determined that the preparation of the image data is not completed (step S10: NO), the control unit 5 repeats step S10.

When it is determined that the preparation of the image data is completed (step S10: YES), in step S11, the control unit 5 returns the transport unit 3 to the standard drive.

Next, in step S12, the control unit 5 controls the paper feed unit 2 and the print unit 4 to start paper feed and printing based on the next print job. After this, the control unit 5 returns to the process of step S5.

If it is determined in step S6 that the next print job has not been received (step S6: NO), in step S13, the control unit 5 stops the transport unit 3. Specifically, the control unit 5 stops the transfer motor 26 and the suction unit 27. This ends a series of operations.

Next, the ink dripping due to the ink mist will be described.

When the head module 32 of the inkjet head 31 ejects ink during printing in the inkjet printing apparatus 1, ink mist is generated. A part of the generated ink mist adheres to a member such as a head module 32 and a head holder (not shown) that holds the head module 32. The ink mist adhering to the head module 32 or the like may agglomerate into a lump of ink due to the influence of the air flow generated by driving the transport unit 3, and may drop out.

FIG. 5 is a diagram for explaining a process in which the ink mist adhering to the head module 32 becomes a lump of ink and drops off.

As shown in the first to third stages from the top of FIG. 5, the small ink droplet 41 formed by the ink mist adhering to the nozzle surface 32a of the head module 32 moves under the wind pressure of the air flow F. Large ink droplets 41 are formed by agglomerating the ink droplets 41 that come into contact with each other. Then, as shown in the lowermost stage of FIG. 4, the enlarged ink droplet 41 falls from the nozzle surface 32a due to the wind pressure of the air flow F. In this way, the ink drops due to the ink mist.

Here, the airflow F shown in FIG. 5 is generated by the movement of the transport belt 21 when the transport unit 3 is driven and the suction of air by the suction unit 27. As for the air flow F, the faster the transport speed of the transport belt 21, the faster the wind speed. Further, as for the air flow F, the larger the air volume of the suction portion 27, the faster the wind speed.

In order to reduce the ink dripping that occurs as described above, in the inkjet printing apparatus 1, as described in the flowchart of FIG. 5, even if the next print job is received at the end of printing based on the print job, the next print job is the same. When the preparation of the image data of the print job is not completed, the transport unit 3 is switched to the low speed drive in order to reduce the wind speed of the airflow generated by the drive of the transport unit 3 until the preparation is completed. .. At this time, the reason why the transport unit 3 is not stopped is to shorten the time until the transport unit 3 is returned to the standard drive and can be fed to the transport unit 3 after the preparation of the image data of the next print job is completed. Is.

As described above, in the inkjet printing apparatus 1, the control unit 5 has already received the next print job at the end of printing based on the print job, and starts printing based on the next print job. When the preparation of the image data is not completed, the transport unit 3 is controlled so as to perform low-speed driving until the preparation is completed.

As a result, the wind speed of the airflow generated by driving the transport unit 3 is reduced from the end of printing based on the print job to the completion of preparation of the image data of the next print job. Therefore, it is possible to reduce that the ink mist adhering to the inkjet head 31 or the like becomes a lump of ink and drops from the inkjet head 31 or the like to the printed matter or the transport unit 3. This makes it possible to reduce the stains on the printed matter and the transport belt 21.

Further, by performing the low-speed drive without stopping the transport unit 3, the transport unit 3 is stopped for the time until the transport unit 3 is returned to the standard drive state after the preparation of the image data of the next print job is completed. It can be shortened compared to the case of making it. Therefore, the time from the end of printing based on the print job to the start of printing based on the next print job can be shortened, so that the decrease in the productivity of the printed matter can be suppressed.

Therefore, according to the inkjet printing apparatus 1, it is possible to reduce the drop of ink on the printed matter and the transport unit 3 while suppressing the decrease in the productivity of the printed matter.

Further, since the transport unit 3 is driven at a low speed from the end of printing based on the print job to the completion of preparation of the image data of the next print job, power consumption and noise can be reduced.

[Second Embodiment]
Next, a second embodiment in which a part of the first embodiment described above is modified will be described.

In the second embodiment, the control unit 5 generates an air flow from the downstream side to the upstream side by making the air volume of the upstream suction unit 28 larger than the air volume of the downstream suction unit 29 when the transport unit 3 is driven at low speed. By doing so, the airflow from the upstream side to the downstream side due to the drive of the transport belt 21 is controlled to be weakened.

Specifically, the control unit 5 controls the air volume of the upstream suction unit 28 to be a predetermined first weak air volume smaller than the standard air volume when the transport unit 3 is driven at low speed, and the air volume of the downstream suction unit 29. Is controlled to be a predetermined second weak air volume smaller than the first weak air volume.

As a result, as shown in FIG. 6, an airflow Fb from the downstream side to the upstream side is generated due to the difference in air volume between the upstream side suction unit 28 and the downstream side suction unit 29. This airflow Fb weakens the airflow Fa from the upstream side to the downstream side due to the movement of the transport belt 21. Therefore, the ink dripping from the inkjet head 31 and the like is further reduced.

Here, the above-mentioned first weak air volume and second weak air volume are preset as air volumes of the upstream suction unit 28 and the downstream suction unit 29, which can generate an air flow Fb that can cancel the air flow Fa, respectively. be.

As described above, in the second embodiment, the control unit 5 increases the air volume of the upstream suction unit 28 to be larger than the air volume of the downstream suction unit 29 when the transport unit 3 is driven at low speed, and is upstream from the downstream side. By generating an airflow to the side, the airflow driven by the transport belt 21 is controlled to be weakened. As a result, the airflow that causes the ink to drop from the inkjet head 31 or the like is weakened, so that the ink drop to the printed matter or the transport unit 3 can be further reduced.

[Other embodiments]
As mentioned above, the invention has been described by the first and second embodiments, but the statements and drawings that form part of this disclosure should not be understood as limiting the invention. This disclosure will reveal to those skilled in the art various alternative embodiments, examples and operational techniques.

In the first and second embodiments described above, the inkjet printing apparatus 1 including the air suction type transport unit 3 has been described. However, the transport unit may hold the print medium on the transport surface by another method. For example, the transport unit may be of the electrostatic transport type. Even in such a transport unit, the productivity of printed matter is increased by performing low-speed driving in which the driving speed is lower than that at the time of printing from the end of printing based on the print job to the completion of preparation of the image data of the next print job. It is possible to reduce the dripping of ink on the printed matter and the transport section while suppressing the decrease in the amount of ink.

In the first embodiment described above, when the transport unit 3 is driven at a low speed, the moving speed of the transport belt 21 is set to a low speed drive speed lower than the print transport speed, and the air volume of the suction unit 27 is set to be smaller than the standard air volume. .. However, when the transport unit 3 is driven at a low speed, the air volume of the suction unit 27 may remain the standard air volume. Even in this case, by setting the moving speed of the transport belt 21 to a low speed drive speed, the airflow generated by the movement of the transport belt 21 is weakened, so that the ink dripping on the printed matter or the transport portion 3 can be reduced. Further, even in this case, the time required to return the transport unit 3 to the standard drive state after the preparation of the image data of the next print job is completed can be shortened as compared with the case where the transport unit 3 is stopped. Therefore, even in this case, it is possible to reduce the drop of ink on the printed matter and the transport unit 3 while suppressing the decrease in the productivity of the printed matter.

As described above, it goes without saying that the present invention includes various embodiments not described here. Therefore, the technical scope of the present invention is defined only by the matters specifying the invention relating to the reasonable claims from the above description.

[Additional Notes]
This application discloses the following inventions.

(Appendix 1)
A transport unit that transports the print medium while holding it on the transport surface,
An inkjet head that ejects ink to the print medium conveyed by the transfer unit,
While controlling the transport unit, when a print job is received, the print job is expanded into an image to generate image data for printing by the inkjet head, and ink is ejected from the inkjet head to a print medium based on the generated image data. By providing a control unit that executes printing based on a print job,
When the control unit has received the next print job at the end of printing based on the print job, and the image data for starting printing based on the next print job has not been prepared, the control unit is concerned. An inkjet printing apparatus characterized in that the transport unit is controlled so as to perform low-speed driving in which the driving speed is lower than that at the time of printing until the preparation of image data is completed.

(Appendix 2)
The transport unit is
A transport belt having a plurality of suction holes and forming the transport surface,
A suction unit that sucks air through the suction holes and sucks and holds the print medium on the transport surface of the transport belt is provided.
The inkjet printing apparatus according to Appendix 1, wherein the control unit drives the suction unit with a smaller air volume than during printing when the transport unit is driven at a low speed.

(Appendix 3)
The suction part is
An upstream suction unit that sucks air through the suction hole,
It is provided on the downstream side of the upstream suction unit in the transport direction of the print medium, and is provided with a downstream suction unit that sucks air through the suction hole.
The control unit causes the air flow of the upstream suction unit to be larger than the air volume of the downstream suction unit to generate an air flow from the downstream side to the upstream side when the transport unit is driven at a low speed. The inkjet printing apparatus according to Appendix 2, wherein the control is performed so as to weaken the air flow from the upstream side to the downstream side by driving the belt.

1 Inkjet printing device 2 Feeding unit 3 Transfer unit 4 Printing unit 5 Control unit 21 Transport belt 21a Suction hole 21b Transport surface 26 Transport motor 27 Suction section 28 Upstream suction section 29 Downstream suction section 31, 31C, 31K, 31M, 31Y Inkjet Head 32 Head Module

Claims (1)

A transport unit that transports the print medium while holding it on the transport surface,
An inkjet head that ejects ink to the print medium conveyed by the transfer unit,
While controlling the transport unit, when a print job is received, the print job is expanded into an image to generate image data for printing by the inkjet head, and ink is ejected from the inkjet head to a print medium based on the generated image data. By providing a control unit that executes printing based on a print job,
The transport unit is
A transport belt having a plurality of suction holes and forming the transport surface,
A suction unit that sucks air through the suction holes and sucks and holds the print medium on the transport surface of the transport belt is provided.
The suction part is
An upstream suction unit that sucks air through the suction hole,
It is provided on the downstream side of the upstream suction unit in the transport direction of the print medium, and is provided with a downstream suction unit that sucks air through the suction hole.
When the control unit has received the next print job at the end of printing based on the print job, and the image data for starting printing based on the next print job has not been prepared, the control unit is concerned. Until the preparation of the image data is completed, the transport unit is controlled so that the drive speed is lower than that at the time of printing.
When the transport unit is driven at low speed, the suction unit is driven with a smaller air volume than during printing.
When the transport section is driven at low speed, the air volume of the upstream suction section is made larger than the air volume of the downstream suction section to generate an air flow from the downstream side to the upstream side, thereby driving the transport belt upstream. An inkjet printing device characterized by controlling the airflow from the side to the downstream side to be weakened.

Images