JP2021146661A - Ink jet printer - Google Patents

Abstract

To reduce an image quality defect.SOLUTION: An ink jet printer comprises: a conveyor belt 12 which is provided with a plurality of suction holes 12a and conveys a supplied sheet; a suction fan 13 which is provided below the conveyor belt 12 and suctions the air from the plurality of suction holes 12a; an ink jet head 11 which discharges ink from a nozzle on the basis of image data including the drop number of each pixel to a sheet P adsorbed and conveyed on the conveyor belt 12 with the suction of the suction fan 13; and an image processing unit 60 which controls the execution of thinning-out processing for thinning out a pixel on each end side and increasing processing for increasing the drop number of the pixel on each end side after thinning-out in accordance with a distance from each end of the sheet conveyed by the conveyor belt 12 to the pixel on each end side in each pixel included in image data.SELECTED DRAWING: Figure 5

Description

The present invention relates to an inkjet printing apparatus that reduces image quality defects.

Some inkjet printing devices are equipped with a transport belt that transports paper below the inkjet head, and prints with ink ejected from the inkjet head while transporting the paper at a predetermined transport speed by the transport belt. .. When the paper is conveyed by the transfer belt, the paper is sucked onto the transfer belt by the suction force of the suction fan provided in the transfer belt. At this time, an air flow that wraps around the paper is generated by suction by the suction fan. Then, the mist generated by the ink ejection accompanies this air flow, and a phenomenon called satellite in which the accompanying mist lands at a place deviated from the ejection position may occur.

Further, depending on the characteristics of the ink, bleeding of the ink that has landed on the paper may occur.

As described above, bleeding of satellites and inks may cause problems of image quality deterioration such as a wide line width and a decrease in recognition rate, particularly when printing a coded image such as a two-dimensional bar code.

In Patent Document 1, the number of pixels on the downstream side of the airflow toward the outside of the paper generated by the suction of the suction fan is thinned out with respect to the number of drops of each pixel, and the number of pixels on the downstream side after thinning is thinned out. An inkjet printing apparatus including an image processing unit for increasing the number is disclosed.

Japanese Unexamined Patent Publication No. 2014-162180

As described above, in the inkjet printing apparatus, an air flow that wraps around the paper is generated by suction by a suction fan. Therefore, the closer it is to the edge of the paper, the more easily it is affected by the entrained airflow.

However, in the inkjet printing apparatus described in Patent Document 1, the influence of the airflow is fully considered because only the airflow generated by the suction of the suction fan toward the outside of the paper is focused and the number of drops of the pixels on the downstream side thereof is thinned out. It was difficult to properly reduce the image quality defect.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an inkjet printing apparatus that reduces image quality defects.

In order to achieve the above object, the first feature of the inkjet printing apparatus according to the present invention is
A transport belt that is provided with multiple suction holes to transport the supplied paper,
A suction means provided below the transport belt and sucking air from the plurality of suction holes.
An ink ejection means that ejects ink from a nozzle based on image data including the number of drops of each pixel with respect to the paper that is attracted and conveyed on the conveying belt by the suction of the suction means.
A thinning process for thinning out the pixels on each end side according to the distance from each end of the paper conveyed by the transfer belt to the pixels on each end side among the pixels included in the image data. It is provided with an image processing means for controlling execution with an increasing process for increasing the number of pixels dropped on each end side after thinning.

According to the features of the inkjet printing apparatus according to the present invention, image quality defects can be reduced.

(A) is a side view of the inkjet printing apparatus according to the embodiment of the present invention, and (b) is a plan view of the inkjet printing apparatus according to the embodiment of the present invention. It is a figure explaining the generation of satellite when the air flow F1 is generated in the inkjet printing apparatus which is one Embodiment of this invention. (A) is a diagram showing the state of satellite generation when the number of ink drops ejected from the inkjet head is 3, and (b) is a diagram showing the state of satellite generation when the number of ink drops ejected from the inkjet head is 5 drops. It is a figure which shows the generation state of the satellite in the case of. It is a figure which shows the functional structure of the inkjet printing apparatus which is one Embodiment of this invention. It is a figure explaining the distance from each end part of the paper to the pixel on each end side of each pixel included in image data. It is explanatory drawing explaining the image thinning process and the drop number increase process by an image processing unit. (A) shows the original image before the thinning process and the increasing process are executed, and (b) shows the printed image when the original image is printed without executing the thinning process and the increasing process. (C) shows an image after the thinning process and the increase process are executed, and (d) shows a printed image when printed based on the image shown in (c). It is a figure which shows the direction of the air flow, and the area in the paper about the whole paper. It is a figure which shows the thinning-out position about the positioning image in the area in the paper P shown in FIG. It is a flowchart which shows the processing content of the image processing in the inkjet printing apparatus which is one Embodiment of this invention.

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. However, it should be noted that the drawings are schematic and differ from the actual ones. In addition, there are parts in which the relations and ratios of the dimensions of the drawings are different from each other.

Further, 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 describes the arrangement of each component and the like as follows. It is not specific to. The technical idea of the present invention can be modified in various ways within the scope of claims.

<Outline configuration of inkjet printing equipment>
The configuration of the inkjet printing apparatus 1 according to the embodiment of the present invention will be described.

FIG. 1 is a configuration diagram showing a configuration of an inkjet printing apparatus 1 according to an embodiment of the present invention. (A) is a side view of the inkjet printing apparatus 1 according to the embodiment of the present invention, and (b) is a plan view of the inkjet printing apparatus 1 according to the embodiment of the present invention.

As shown in FIG. 1A, the inkjet printing apparatus 1 includes an inkjet head 11 for ejecting ink and a transport belt 12 provided below the inkjet head 11 for transporting paper P. Further, below the transport belt 12, a suction fan 13 installed corresponding to the back surface of the transport road surface of the paper P is provided.

The paper P is sucked onto the transport belt 12 by the suction fan 13 and is conveyed at a predetermined transfer speed. An image is printed on the paper P by the ink ejected from the inkjet head 11.

Further, the transfer belt 12 is provided with a plurality of suction holes 12a, and in a region on the transfer belt 12 where there is no paper P, the transfer belt 12 is guided from the direction of the inkjet head 11 through the suction holes 12a to the direction of the suction fan 13. Airflow F is generated.

In the region with the paper P on the transport belt 12, as shown in FIG. 1B, an air flow is generated from the region A with the paper P on the transport belt 12 to the region B without the paper P. Specifically, as shown in FIGS. 1A and 1B, the airflows F1, F2, F3, respectively, wrap around the paper P from the head 11 toward the closest end on the paper P. F4 occurs.

FIG. 2 is a diagram illustrating a satellite generation state when an air flow F1 is generated in the inkjet printing apparatus 1. (A) is a diagram showing the state of satellite generation when the number of ink drops ejected from the inkjet head 11 is 3, and (b) is the number of ink drops ejected from the inkjet head 11. It is a figure which showed the generation state of the satellite when is 5 drops.

As shown in FIG. 2A, when the inks d1 to d3 are ejected from the inkjet head 11, mists m1 and m2 are generated accordingly. When the mists m1 and m2 land on the paper P, they become satellite s1. When the number of satellites s1 increases, the sharpness of the image is lost. In particular, when printing a coded image such as a two-dimensional bar code, problems such as a wide line width and a decrease in recognition rate may occur.

More specifically, when the number of drops of ink ejected from the inkjet head 11 is small, the distance between each drop becomes long, so that the ink is interrupted and mist is likely to be generated.

For example, when the number of drops is 3, the distance between the drops d1 and the drops d2 is long, and mist m1 is likely to be generated. Similarly, mist m2 is likely to be generated between the drop d2 and the drop d3. Therefore, the amount of mist m1 and m2 that land on the paper P increases, and the amount of satellite s1 increases.

On the other hand, as shown in FIG. 2B, when the number of ink drops ejected from the inkjet head 11 is large (here, 5 drops), the distance between each drop becomes short, so that the ink is interrupted. It is difficult and mist is less likely to be generated. Specifically, the intervals between the drops d5 and the drops d9 are short, the amount of mist m5 and m6 generated is small, and the satellite s2 is small. As described above, the larger the number of ink drops ejected from the inkjet head, the smaller the number of satellites tends to be.

Further, the larger the number of ink drops ejected from the inkjet head, the more likely it is that ink bleeding will occur. More specifically, if the number of drops is increased excessively at the edge of the image, the blur spreads. For example, when printing a coded image such as a two-dimensional bar code, there may be a problem that the line width of the bar becomes wide and the recognition rate decreases.

Therefore, the inkjet printing apparatus 1 appropriately controls the thinning process of thinning out the pixels and the increasing process of increasing the number of pixel drops after the thinning out, thereby suppressing the generation of satellites and preventing recognition failure due to bleeding. Reduce.

<Functional configuration of inkjet printing device 1>
Next, the functional configuration of the inkjet printing apparatus 1 will be described.

FIG. 3 is a diagram showing a functional configuration of the inkjet printing apparatus 1.

As shown in the figure, the inkjet printing device 1 includes an inkjet head 11, a transport belt 12, a suction fan 13, an image processing unit 60, a storage unit 70, a control unit 80, and an operation unit 90. .. Of the above configurations, the inkjet head 11, the conveyor belt 12, and the suction fan 13 are as described above.

The storage unit 70 is composed of, for example, a non-volatile semiconductor or the like, and stores various control programs or the like executed by the control unit 80.

The control unit 80 controls each configuration included in the inkjet printing device 1. For example, the control unit 80 controls the inkjet head 11, the transport belt 12, and the suction fan 13 to suck and transport the paper P on the transport belt 12, and prints an image on the paper P based on the image data. Print.

The operation unit 90 includes a display / input panel (not shown), a start key for starting printing, a stop key for stopping printing, a numeric keypad for inputting the number of prints, etc. (none of which are shown). It is provided with various operation keys of the above, and an operation signal based on a user operation is supplied to the control unit 80.

The image processing unit 60 controls the image thinning process and the drop number increasing process according to the distance from each end of the paper P conveyed by the conveying belt 12 to the pixels.

Hereinafter, the function of the image processing unit 60 will be described in detail.

Function of Image Processing Unit 60 FIG. 4 is a diagram illustrating the distance from each end of the paper P to the pixels on the end side.

As shown in FIG. 4, the paper P includes edges E1 to E4. The image printed on the paper P includes an image D1 that constitutes a two-dimensional bar code image. The image D1 has a rectangular shape, and the pixel on the end E1 side is the end side pixel D11, the pixel on the end E2 side is the end side pixel D12, and the pixel on the end E3 side is the end side pixel. The pixels on the D13 and end E4 sides are referred to as end side pixels D14. Further, the distance L1 is set from the end E1 to the end side pixel D11, the distance L2 is set from the end E2 to the end side pixel D12, and the distance L3 is set from the end E3 to the end side pixel D13. The distance L4 is defined as the distance from E4 to the end side pixel D14.

The closer each pixel constituting the image D1 is to the ends E1 to E4, the greater the influence of the airflow F, so that the number of satellites increases.

Therefore, the image processing unit 60 controls the execution of the thinning process and the increase process according to the distances L1 to L4. Here, the thinning process is a process of thinning out one or more end-side pixels among the end-side pixels D11 to D14, and the increase process is a process of thinning out the number of pixels on each end side after thinning out. It is a process to increase.

In the example shown in FIG. 4, since the distance L2 and the distance L3 are short, the influence of the airflow F on the end side pixel D12 and the end side pixel D13 becomes large. On the other hand, since the distance L1 and the distance L4 are sufficiently long, the influence of the airflow F on the end side pixel D11 and the end side pixel D14 becomes small.

Therefore, the image processing unit 60 executes the thinning process on the end side pixel D12 and the end side pixel D13, and executes the increase process after the thinning.

FIG. 5 is an explanatory diagram illustrating the thinning process and the increase process by the image processing unit 60. Here, a positioning image provided at the lower left for positioning the two-dimensional code image will be described as an example. FIG. 5A shows an original image before the thinning process and the increasing process are executed, and FIG. 5B shows a case where the original image is printed without executing the thinning process and the increasing process. (C) shows the image after the thinning process and the increase process are executed, and (d) shows the case of printing based on the image shown in (c). Shows a printed image. In FIG. 5, the pixels indicated by the black circles ● are the pixels to be printed, and the pixels indicated by the white circles ◯ are the pixels to be thinned out.

In the example of the original image shown in FIG. 5A, the original image is rectangular and has a rectangular blank area 101 inside. That is, the pixels are formed so as to surround the blank area 101 with a line width R having 4 dots.

As shown in FIG. 5 (b), when the original image shown in FIG. 5 (a) is printed without executing the thinning process and the increase process, the end side pixel D12 spreads in the downstream direction of the air flow F2. , The end side pixel D13 spreads in the downstream direction of the airflow F3. In addition, bleeding of the ejected ink occurs. As a result, the line width R2 becomes thicker than the line width R1, and the image may not be recognized accurately.

Therefore, as shown in FIG. 5C, the image processing unit 60 is close to the edge of the paper, and the landing position is displaced due to the influence of the air flow, and the margins are conspicuously dirty. The thinning process is executed for the side pixel D13. Then, the image processing unit 60 increases the number of drops of the pixels D22 and D23 on the end portions E2 and E3 sides after thinning by one drop.

As a result, as shown in FIG. 5D, the number of drops of the pixels of the end sides 101a and 101d and the pixels of D12 and D13 increases, so that it becomes difficult to move due to the air flow, and the mist accompanying ink ejection to the pixels D22 and D23. The amount can be reduced. Further, even if ink bleeding occurs due to ink ejection to pixels D22 and D23 to form images S12 and S13, the bleeding occurs after thinning out, so that the line width R3 is as shown in FIG. 5 (d). It becomes. Since the line width R3 is subjected to the thinning process and the increase process, the line width R3 is printed with the same line width as the line width R1 of the original image without being widened as in the line width R2.

Further, as shown in FIG. 5, when the image is a rectangular image such as a positioning image of a two-dimensional code image and has a rectangular blank area 101 inside, a predetermined inner side is determined. For the pixels, the thinning process and the increase process may be executed. More details are as follows.

For example, as shown in FIG. 5C, since the distance L2 and the distance L3 are shorter than the predetermined threshold values, the influence of the airflow F on the end side pixels D12 and the end side pixels D13 becomes large, so that the paper P is used. As the end portion, the end portion E2 and the end portion E3 are targeted.

The blank area 101 of the image shown in FIG. 5C has four end sides 101a to 101d. Assuming that the pixel on the outer end side is the end side pixel D12, of the four end sides 101a to 101d, the end side 101a and the end side 101b face the end side pixel D12.

Of the edge 101a and the edge 101b, the edge 101a that is closer to the edge of the paper and the landing position is displaced due to the influence of the air flow and the margin is conspicuous is the edge 101a far from the edge side pixel D12.

Therefore, the image processing unit 60 thins out the pixels of the end side 101a according to the distance L6 from the end side 101a to the end E2 of the opposing paper P, and the number of drops of the pixel D221 on the end E2 side after the thinning out. Is increased by 1 drop.

Similarly, assuming that the pixel on the outer end side shown in FIG. 5C is the end side pixel D13, of the four end sides 101a to 101d, the one facing the end side pixel D13 is The end side 101c and the end side 101d.

Of the edge 101c and the edge 101d, the edge 101d that is closer to the edge of the paper and the landing position is displaced due to the influence of the air flow and the margin is conspicuous is the edge 101d far from the edge side pixel D13.

Therefore, the image processing unit 60 thins out the pixels of the end side 101d according to the distance L7 from the end side 101d to the end E3 of the opposing paper P, and the number of drops of the pixels D231 on the end E3 side after the thinning out. Is increased by 1 drop.

Summarizing the above, the image processing unit 60 sets the distances L1 to L4 from the pixels on the outer edge of the paper to the edge of the opposite paper P in the image data, and the outer edge of the edge of the blank area 101. The edge on the blank area 101 side is controlled by controlling the execution of the thinning process and the increase process according to the distances L6 and L7 from the pixel on the edge farther from the edge to the edge of the opposite paper. Edge processing can be performed.

As a result, as shown in FIG. 5D, the printed image is printed with a line width R3 equivalent to the line width R1 of the original image.

FIG. 6 is a diagram showing the direction of the air flow and the region in the paper P for the entire paper P, and FIG. 7 is a diagram showing the thinning position of the positioning image in the region in the paper P shown in FIG. Is.

As shown in FIG. 6, when the paper P is divided into nine regions from the region AA to the region CC, the influence of the air flow toward the paper edge in the direction of the arrow becomes large.

FIG. 7A shows the thinning position in the AA region shown in FIG. 6, FIG. 7B shows the thinning position in the AB region, and FIG. 7C shows the thinning position in the AC region. The position is shown, FIG. 7 (d) shows the thinning position in the BA region, FIG. 7 (e) shows the thinning position in the BB region, and FIG. 7 (f) shows the thinning position in the BC region. The thinning position is shown, FIG. 7 (g) shows the thinning position in the CA region, FIG. 7 (h) shows the thinning position in the CB region, and FIG. 7 (i) shows the CC region. Indicates the thinning position in. In FIG. 7, the pixels indicated by the black circles ● are the pixels to be printed, and the pixels indicated by the white circles ◯ are the pixels to be thinned out.

For example, as shown in FIG. 7A, in the AA region, the end side pixel D31 on the end E1 side, the end side pixel D33 on the end E3 side, and the end in the blank area 101, which are indicated by white circles. The thinning process is executed for the pixel D41 at the end farther from the pixel D31 and the pixel D43 at the end farther from the end pixel D33 in the blank area 101, and the pixels on each end after being thinned out. The increase process is executed for.

As shown in FIGS. 7 (b) to 7 (i), similarly, the thinning process is executed for the pixels indicated by the white circles in the nine regions of regions AB to CC, and each end portion after thinning is performed. The increase process is executed for the pixel on the side.

As described above, the image processing unit 60 thins out each pixel according to the distance from each end of the paper conveyed by the conveying belt 12 to each pixel, thereby preventing the line width from expanding due to bleeding. Further, by increasing the number of pixel drops on each end side after thinning, the generation of satellites is suppressed and the line width expansion is prevented. This prevents the line width from expanding due to bleeding and improves the print reproducibility of the original image. In particular, poor recognition of a coded image such as a two-dimensional bar code is suppressed.

As described above, when the number of pixels dropped on each end side is large, satellites are unlikely to occur. Therefore, the image processing unit 60 may perform thinning processing and increasing processing according to the distance from the end portion to the pixel and the number of pixels dropped on each end portion side. For example, the image processing unit 60 may execute the thinning process and the increase process when the number of drops of one pixel on the edge side of the paper P is smaller than 2 drops, or the image processing unit 60 may execute the thinning process and the increase process on the edge side of the paper P. When the number of drops of 2 pixels is smaller than 3 drops, the thinning process and the increase process may be performed.

FIG. 8 is a flowchart showing image processing in the inkjet printing apparatus 1. The following steps are all executed by the image processing unit 60.

In step S101, it is determined whether or not the image data includes the two-dimensional bar code, and if it is not included, the process is repeated, and if it is included, the process proceeds to step S103 to extract the two-dimensional bar code.

In step S105, the distance from each end of the paper P conveyed by the transfer belt 12 to the pixel on each end side of the paper P among the pixels of the two-dimensional bar code is calculated.

In step S107, it is determined whether or not there is an edge whose calculated distance is equal to or less than a predetermined threshold value (predetermined value) (the predetermined threshold value is based on whether or not the influence of the air flow affects the reading accuracy of the barcode. If all the calculated distances are equal to or greater than the predetermined value, the process ends, and if there is a side equal to or less than the predetermined value, the process proceeds to step S109.

In step S109, it is determined whether or not the number of drops of one pixel on the edge side of the paper P is smaller than 2 drops, and if it is 2 drops or more, the image processing is terminated (because satellites are unlikely to occur) and 2 If it is less than the drop, the process proceeds to step S111.

In step S111, one pixel on the side whose calculated distance is equal to or less than the threshold value is thinned out. At this time, as described with reference to FIG. 5, when the image data includes a positioning image, the pixels at a predetermined end side of the blank area 101 may be thinned out.

In step S113, the number of pixel drops after thinning is increased by one drop.

In the above flowchart, the image processing unit 60 executed the thinning process and the increase process for the two-dimensional bar code, but the target is not only the two-dimensional bar code but also all kinds of character data, photographic data, and the like. You may want to do this for the image.

Further, the coded image included in the image data may be not only a rectangular two-dimensional bar code but also another coded image. For example, it may be a polygon other than a rectangle such as a triangle instead of a rectangle, or it may be a circle.

Further, in one embodiment of the present invention, the image processing unit 60 thins out one pixel on the side whose calculated distance is equal to or less than the threshold value, but the present invention is not limited to this, and a plurality of pixels may be thinned out.

The image processing unit 60 has increased the number of pixel drops after thinning by one drop, but the present invention is not limited to this. The number of drops may be increased according to the degree of ink bleeding onto the paper P. For example, the storage unit 70 stores the ink, the type of paper, and the degree of bleeding in association with each other as a bleeding table. The degree of bleeding is a coefficient indicating how much bleeding occurs when printed, and the larger the value, the more bleeding occurs.

The image processing unit 60 sets a larger number of drops as the degree of bleeding is smaller and a smaller number of drops as the degree of bleeding is larger, based on the type of ink and paper P used and the bleeding table.

Further, in the paper transport direction, the rear side is easily affected by the air flow generated by the transport. Therefore, the number of pixels to be thinned out may be increased for the pixels on the rear side in the paper transport direction.

(Additional note)
The present application discloses the following inventions.

(Appendix 1)
A transport belt that is provided with multiple suction holes to transport the supplied paper,
A suction means provided below the transport belt and sucking air from the plurality of suction holes.
An ink ejection means that ejects ink from a nozzle based on image data including the number of drops of each pixel with respect to the paper that is attracted and conveyed on the conveying belt by the suction of the suction means.
A thinning process for thinning out the pixels on each end side according to the distance from each end of the paper conveyed by the transfer belt to the pixels on each end side among the pixels included in the image data. An image processing means that controls execution with an increase process that increases the number of pixel drops on each end side after thinning out.
An inkjet printing device characterized by being equipped with.

This reduces the amount of satellites generated and prevents the line width from becoming wider due to satellites and bleeding. Since the print reproducibility of the original image is improved, it is possible to reduce the recognition failure of the coded image such as the two-dimensional bar code.

(Appendix 2)
The image processing means
Controlling the execution of the thinning process and the increase process according to the distance to the pixel on each end side of each pixel included in the image data and the number of drops of the pixel on each end side. The inkjet printing apparatus according to Appendix 1, wherein the inkjet printing apparatus is characterized by the above.

As a result, the thinning process and the increase process can be executed only when the number of pixels dropped on each end side is small and satellites are likely to occur.

(Appendix 3)
The image data is rectangular, has a rectangular blank area inside, and has a rectangular blank area.
The image processing means
The distance from the pixel on the outer edge of the image data to the opposite edge of the paper and the blank on the edge of the blank area facing the outer edge and far from the outer edge. The inkjet printing apparatus according to Appendix 1, wherein the execution of the thinning process and the increase process is controlled according to the distance from the pixel on the edge of the region to the edge of the opposite paper.

As a result, for an image that is rectangular and has a rectangular blank area inside, such as a positioning image of a two-dimensional bar code, the pixels on the downstream side of the blank area are thinned out. Since the increase process can be executed, the recognition failure can be further reduced.

(Appendix 4)
An inkjet printing apparatus having an image processing means for thinning out the pixels on the end side according to the distance from one end of the paper conveyed by the transport belt to the pixels on the end side.

This reduces the amount of satellites generated and prevents the line width from becoming wider due to satellites and bleeding. Since the print reproducibility of the original image is improved, it is possible to reduce the recognition failure of the coded image such as the two-dimensional bar code.

(Appendix 5)
The image processing means
The inkjet printing apparatus according to Appendix 4, wherein the number of drops of pixels on the end side remaining after the thinning is increased.

As a result, the amount of satellites generated can be further reduced, and the print reproducibility of the original image can be further improved.

1 Inkjet printing device 11 Inkjet head 12 Conveying belt 12a Suction hole 13 Suction fan 60 Image processing unit 70 Storage unit 80 Control unit 90 Operation unit

Claims (5)

A transport belt that is provided with multiple suction holes to transport the supplied paper,
A suction means provided below the transport belt and sucking air from the plurality of suction holes.
An ink ejection means that ejects ink from a nozzle based on image data including the number of drops of each pixel with respect to the paper that is attracted and conveyed on the conveying belt by the suction of the suction means.
A thinning process for thinning out the pixels on each end side according to the distance from each end of the paper conveyed by the transfer belt to the pixels on each end side among the pixels included in the image data. An image processing means that controls execution with an increase process that increases the number of pixel drops on each end side after thinning out.
An inkjet printing device characterized by being equipped with. The image processing means
Controlling the execution of the thinning process and the increase process according to the distance to the pixel on each end side of each pixel included in the image data and the number of drops of the pixel on each end side. The inkjet printing apparatus according to claim 1. The image data is rectangular, has a rectangular blank area inside, and has a rectangular blank area.
The image processing means
The distance from the pixel on the outer edge of the image data to the opposite edge of the paper and the blank on the edge of the blank area facing the outer edge and far from the outer edge. The inkjet printing apparatus according to claim 1, wherein the execution of the thinning process and the increase process is controlled according to the distance from the pixel on the edge of the region to the edge of the opposite paper. An inkjet printing apparatus having an image processing means for thinning out the pixels on the end side according to the distance from one end of the paper conveyed by the transport belt to the pixels on the end side. The image processing means
The inkjet printing apparatus according to claim 4, wherein the number of drops of the pixels on the end side remaining after the thinning is increased.

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