CN118438815A

CN118438815A - Double-sided ink-jet printing method, device and equipment

Info

Publication number: CN118438815A
Application number: CN202410502363.9A
Authority: CN
Inventors: 张朝胜; 张仁苏
Original assignee: Suzhou Senhong Technology Co ltd
Current assignee: Suzhou Senhong Technology Co ltd
Priority date: 2024-04-25
Filing date: 2024-04-25
Publication date: 2024-08-06

Abstract

The invention discloses a double-sided ink-jet printing method, device and equipment, and relates to the technical field of ink-jet printing. According to the method, the first printing trolley and the second printing trolley are driven to synchronously move in opposite directions or in opposite directions at the same printing height based on one driving mechanism to realize simultaneous printing of the front side and the back side of the printing medium, compared with the existing double-sided ink-jet printing technology, the method does not need to wait for ink drying or perform additional overturning operation, can remarkably shorten the printing time, improves the printing efficiency, and enables the time and the position of the ink penetrating into the front side and the back side of the printing medium to be close when the front side and the back side are synchronously printed, so that tension difference of the front side and the back side caused by ink penetration is reduced, the influence of the tension difference on the printing effect is reduced, and the printing quality is improved. In addition, the data processing mode in printing in the method is simple and efficient, can better meet the requirement of double-sided ink-jet printing, improves the printing quality and efficiency, and improves the user satisfaction.

Description

Double-sided ink-jet printing method, device and equipment

Technical Field

The present invention relates to the field of inkjet printing technologies, and in particular, to a method, an apparatus, and a device for duplex inkjet printing.

Background

In digital inkjet printing applications, duplex inkjet printing is a technique of forming images by inkjet printing on both sides of a print medium such as paper, textile cloth, glass, acryl, etc., respectively. In general, a conventional inkjet printing apparatus can only jet ink on one side of a printing medium, and the other side needs to wait for the ink to dry before performing reverse printing, which wastes time. In addition, referring to the double-sided printing method disclosed in the application publication No. CN109334254a, the patent name "double-sided printing method and double-sided printing machine", the existing double-sided printing needs to be completed by a complex Rao Bu structure and by using two scanning mechanisms of front and back, that is, the front scanning mechanism is controlled to print the front by inkjet, and then the back scanning mechanism is assisted by a winding roller to print the back by inkjet, so as to realize double-sided printing. This printing mode has the following drawbacks: if one side is printed first and then is permeated with ink, the side permeated with ink can obviously change in tension and quality, so that the tension of two sides of a printing medium is different, the accuracy of the transmission system or the collecting and discharging system in front and back transmission can be affected, and because two scanning mechanisms are used, two positioning mechanisms (such as a grating ruler) are required to be used for carrying out position positioning for the ignition of a spray head, the consistency of mechanical rigidity and errors of the two positioning mechanisms is difficult to ensure, and errors can be caused in printing of double-sided images, so that the printing quality is affected.

Disclosure of Invention

In view of the above, the embodiments of the present invention provide a method, an apparatus, and a device for dual-sided inkjet printing, which are used to solve the problems of low dual-sided inkjet printing efficiency and poor printing quality in the prior art.

In a first aspect, an embodiment of the present invention provides a duplex inkjet printing method applied to a duplex inkjet printing apparatus, wherein the duplex inkjet printing apparatus includes a first print carriage and a second print carriage, a print medium is vertically disposed between the first print carriage and the second print carriage, the first print carriage and the second print carriage are reciprocally movable in a main scanning direction under the drive of the same driving mechanism, the first print carriage is configured to eject ink to form an image on a front side of the print medium, and the second print carriage is configured to eject ink to form an image on a back side of the print medium, the method comprising:

acquiring an image to be printed, and performing rasterization processing on the image to be printed to obtain first print data;

Expanding the first printing data to obtain second printing data;

Extracting third print data and fourth print data from the second print data, respectively;

performing data processing on the fourth printing data to obtain fifth printing data;

And respectively sending the third printing data and the fifth printing data to the first printing trolley and the second printing trolley, driving the first printing trolley and the second printing trolley to synchronously move in opposite directions or in opposite directions at the same printing height, and respectively spraying ink to the front and back sides of the printing medium to form images.

Preferably, the first print data includes first black channel data, first cyan channel data, first magenta channel data, and first yellow channel data each having N rows, and the expanding the first print data to obtain the second print data includes:

Respectively copying first black channel data, first cyan channel data, first magenta channel data and first yellow channel data of an ith row in the first printing data to obtain second black channel data, second cyan channel data, second magenta channel data and second yellow channel data of the ith row;

Inserting the second black channel data, the second cyan channel data, the second magenta channel data and the second yellow channel data of the ith row into the first black channel data, the first cyan channel data, the first magenta channel data and the first yellow channel data of the ith row and the (i+1) th row to obtain the second printing data;

Wherein i=0, 1,2, … … N-1, N is a natural number of 1 or more.

Preferably, the extracting the third print data and the fourth print data from the second print data includes:

Sequentially extracting the first black channel data, the first cyan channel data, the first magenta channel data, and the first yellow channel data from the second print data as the third print data in line number;

And extracting second black channel data, second cyan channel data, second magenta channel data and second yellow channel data, which are in one-to-one correspondence with the number of lines of the first black channel data, the first cyan channel data, the first magenta channel data and the first yellow channel data in the third print data, from the second print data as the fourth print data.

Preferably, the data processing of the fourth print data to obtain fifth print data includes:

mirror image processing is carried out on the fourth printing data, and mirror image printing data are obtained;

Judging whether the tail of each line of data in the mirror image printing data contains blank data or not;

if yes, placing the blank data at the front end of each row of data to obtain the fifth printing data;

If not, the mirror image printing data is the fifth printing data.

Preferably, after the fourth print data is subjected to data processing to obtain fifth print data, the method further includes:

Controlling the first printing trolley and the second printing trolley to print a first test image and a second test image on the front side and the back side of the printing medium respectively according to third printing data and fifth printing data;

Acquiring vertical alignment deviation of the first test image and the second test image;

Inserting or deleting a plurality of blank data at the front end of each row of data in the third printing data and/or the fifth printing data according to the vertical alignment deviation;

And/or:

acquiring horizontal alignment deviation of the first test image and the second test image;

and inserting or deleting a plurality of rows of blank data in the third printing data and/or the fifth printing data according to the horizontal alignment deviation.

Preferably, before the third print data and the fifth print data are respectively sent to the first print carriage and the second print carriage, the first print carriage and the second print carriage are driven to synchronously move in opposite directions from two ends of the print medium at the same print height, and ink is ejected to the front and back sides of the print medium to form images, the method further comprises:

acquiring the maximum scanning width of the first printing trolley in the main scanning direction, and marking the maximum scanning width as a first width;

Acquiring the width of the image to be printed in the main scanning direction, and marking the width as a second width;

And acquiring initial printing positions of the first printing trolley and the second printing trolley according to the first width and the second width.

Preferably, the first print data is composed of dot data, and before the expanding the first print data to obtain the second print data, the method further includes:

acquiring the total ink quantity corresponding to the first printing data;

Determining preferred values of the amounts of ink carried by the front and back sides of the print medium, respectively, recorded as a first preferred ink amount and a second preferred ink amount, respectively;

And adjusting the ink value corresponding to the dot data according to the total ink quantity, the first preferred ink quantity and the second preferred ink quantity.

Preferably, the dot data includes large dot data, medium dot data and small dot data, and the corresponding ink amounts are recorded as a first ink amount, a second ink amount and a third ink amount, respectively, wherein the first ink amount > the second ink amount > the third ink amount, and the adjusting the ink value corresponding to the dot data according to the total ink amount and the first and second preferred ink amounts includes:

Judging whether a first difference value between the total ink quantity and the first preferred ink quantity is greater than or equal to a preset threshold value and/or whether a second difference value between the total ink quantity and the second preferred ink quantity is greater than or equal to the preset threshold value;

if yes, acquiring an ink quantity adjusting value according to the first difference value and/or the second difference value;

any one or more of the first ink amount, the second ink amount, and the third ink amount is adjusted according to the ink amount adjustment value.

In a second aspect, an embodiment of the present invention provides a duplex inkjet printing apparatus applied to a duplex inkjet printing apparatus, wherein the duplex inkjet printing apparatus includes a first print carriage and a second print carriage, a print medium is vertically disposed between the first print carriage and the second print carriage, the first print carriage and the second print carriage are reciprocally movable in a main scanning direction under the drive of the same driving mechanism, the first print carriage is configured to eject ink to form an image on a front side of the print medium, and the second print carriage is configured to eject ink to form an image on a back side of the print medium, the apparatus comprising:

the data acquisition module is used for acquiring an image to be printed, and carrying out rasterization processing on the image to be printed to obtain first print data;

The data expansion module is used for expanding the first printing data to obtain second printing data;

A data extraction module for extracting third print data and fourth print data from the second print data, respectively;

The data processing module is used for carrying out data processing on the fourth printing data to obtain fifth printing data;

and the printing module is used for respectively sending the third printing data and the fifth printing data to the first printing trolley and the second printing trolley, driving the first printing trolley and the second printing trolley to synchronously move oppositely or reversely at the same printing height and respectively spraying ink to the front surface and the back surface of the printing medium to form images.

In a third aspect, an embodiment of the present invention provides a duplex inkjet printing apparatus, where the duplex inkjet printing apparatus includes a first print carriage and a second print carriage, a print medium is vertically disposed between the first print carriage and the second print carriage, the first print carriage and the second print carriage are reciprocally movable in a main scanning direction under the drive of the same driving mechanism, the first print carriage is configured to eject ink onto a front side of the print medium to form an image, and the second print carriage is configured to eject ink onto a back side of the print medium to form an image; the double-sided inkjet printing apparatus further includes: at least one processor, at least one memory and computer program instructions stored in the memory, which when executed by the processor, implement the method as in the first aspect of the embodiments described above.

In a fourth aspect, embodiments of the present invention provide a storage medium having stored thereon computer program instructions which, when executed by a processor, implement a method as in the first aspect of the embodiments described above.

In summary, the beneficial effects of the invention are as follows:

According to the double-sided ink-jet printing method, the device and the equipment provided by the embodiment of the invention, the first printing trolley and the second printing trolley are driven to synchronously move in opposite directions or in opposite directions at the same printing height based on one driving mechanism to realize the simultaneous printing of the front side and the back side of a printing medium. In addition, the data processing mode in printing in the method is simple and efficient, can better meet the requirement of double-sided ink-jet printing, improves the printing quality and efficiency, and improves the user satisfaction.

Drawings

In order to more clearly illustrate the technical solution of the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be briefly described, and it is within the scope of the present invention to obtain other drawings according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic configuration diagram of a duplex inkjet printing apparatus in an embodiment of the present invention.

FIG. 2 is a schematic illustration of print media placement in an embodiment of the invention.

Fig. 3 is a flow chart of a method of duplex inkjet printing according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of first print data in an embodiment of the present invention.

Fig. 5 is a schematic diagram of second print data in an embodiment of the present invention.

FIG. 6 is a schematic illustration of front and back image misalignment in an embodiment of the invention.

FIG. 7 is a schematic diagram of data processing in an embodiment of the invention.

Fig. 8a is a schematic diagram of front and back image alignment in an embodiment of the invention.

Fig. 8b is a schematic diagram of alignment deviation in an embodiment of the invention.

FIG. 9 is a schematic illustration of centered printing in an embodiment of the invention.

Fig. 10 is a schematic structural view of a duplex inkjet printing apparatus according to an embodiment of the present invention.

Fig. 11 is a schematic structural view of a control system of a duplex inkjet printing apparatus according to an embodiment of the present invention.

Detailed Description

Features and exemplary embodiments of various aspects of the present invention will be described in detail below, and in order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely configured to illustrate the invention and are not configured to limit the invention. It will be apparent to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the invention by showing examples of the invention.

It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

Example 1

The embodiment of the invention provides a double-sided ink jet printing device, as shown in fig. 1, the double-sided ink jet printing device comprises a first printing trolley 5, a second printing trolley 6 and a cross beam 4, wherein a synchronous belt 3, a driving wheel 1 and a driven power 2 are arranged in the cross beam 4, a driving mechanism (not shown) drives the driving wheel 1 to rotate and simultaneously drives the driven wheel 2 to rotate through the synchronous belt 3, the first printing trolley 5 and the second printing trolley 6 are respectively arranged on the synchronous belt 3 of the cross beam 4, for example, the first printing trolley 5 is arranged on the front side 41, the second printing trolley 6 is arranged on the rear side 42, and the synchronous belt 3 can drive the first printing trolley 5 to reciprocate along a main scanning direction X (also called a printing direction) on the front side 41 and the second printing trolley 6 on the rear side 42. The double-sided ink jet printing system provided by the embodiment of the invention does not need a double-beam, a double-control system and a double-driving structure, can effectively reduce the cost, and can achieve the high-quality double-sided ink jet printing effect under the conditions of a low-cost machine type structure and a control system.

As shown in fig. 2, when double-sided printing is required, the printing medium 8 passes through the cross beam 4 and the synchronous belt 3 and is vertically (perpendicular to the horizontal plane) arranged between the first printing carriage 5 and the second printing carriage 6, preferably, the printing origins (i.e. the printing starting points) of the first printing carriage 5 and the second printing carriage 6 are respectively arranged at two ends of the cross beam 4, for example, the printing origin of the first printing carriage 5 is arranged at the right end 43 of the cross beam 4, the printing origin of the second printing carriage is arranged at the left end 44 of the cross beam 4, and when the driving structure drives the driving wheel 1 to rotate and drives the first printing carriage 5 to move from left to right through the synchronous belt 3, the second printing carriage 6 is driven to synchronously move from left to right. Because the first printing trolley 5 and the second printing trolley 6 are arranged on the same cross beam, the printing heights of the first printing trolley and the second printing trolley are the same relative to the printing medium, so that the front and back ink-jet printing is carried out on the same height position of the printing medium at the same time, the time and the position of the ink penetrating into the front and back surfaces of the printing medium are close, the tension difference of the front and back surfaces caused by the sequential penetration of the ink is reduced, and the influence of the tension difference on the printing effect is reduced. In addition, the data transmission mode of the double-sided ink jet printing equipment during printing is similar to that of the single-sided ink jet printing equipment, and special data processing is only needed for the printing data on the back side, so that development cost and trial-and-error cost are greatly reduced, a user can be helped to quickly switch from single-sided ink jet printing to double-sided ink jet printing, development period and trial-and-error cost are furthest reduced, and quick iterative economic benefit is brought to the user.

Based on the above-mentioned double-sided inkjet printing apparatus, referring to fig. 3, an embodiment of the present invention further provides a double-sided inkjet printing method, where the double-sided inkjet printing method specifically includes:

S1, acquiring an image to be printed, and carrying out rasterization processing on the image to be printed to obtain first print data;

S2, expanding the first printing data to obtain second printing data;

s3, respectively extracting third printing data and fourth printing data from the second printing data;

s4, carrying out data processing on the fourth printing data to obtain fifth printing data;

And S5, the third printing data and the fifth printing data are respectively sent to the first printing trolley and the second printing trolley, the first printing trolley and the second printing trolley are driven to synchronously move oppositely or reversely at the same printing height, and ink is respectively sprayed to the front surface and the back surface of the printing medium to form images.

In the embodiment of the invention, how to control the double-sided ink jet printing device to perform double-sided printing is described by taking printing of double-sided images which are identical on both sides and mirror images of each other in a printing medium as an example. Specifically, an image to be printed is first obtained, where the image to be printed may be a bitmap or a vector image. And inputting the image to be printed into an image rasterizing processor (such as RIP software) of an upper computer (such as a PC) of the double-sided ink-jet printing device to perform rasterizing processing, and acquiring printing data in a PRN format which can be identified by the double-sided ink-jet printing device, and recording the printing data as first printing data. Since the double-sided printing is required, the first print data is printed on only one side thereof, and therefore the first print data needs to be expanded to obtain print data sufficient for double-sided printing. The second printing data for double-sided printing is obtained after the first printing data are expanded, when printing is carried out, the second printing data are required to be split while printing is carried out, third printing data for printing the front side in the second printing data are extracted and distributed to the first printing trolley, fourth printing data for printing the back side are extracted and distributed to the second printing trolley, and because the back side image corresponds to the front side image in a mirror image mode, the fourth printing data are sent to the second printing trolley for data processing to obtain fifth printing data before the fourth printing data are sent to the second printing trolley, and therefore the image can be printed on the back side of a printing medium correctly. In addition, in order to reduce the influence of the tension difference on the printing effect, in the embodiment of the invention, the first print trolley and the second print trolley are respectively arranged at two ends of the printing medium before printing, as shown in fig. 2, the first print trolley is arranged at the left end of the printing medium, the second print trolley is arranged at the right end of the printing medium, the printing (position) of the first print trolley and the second print trolley is the same, after the first print trolley receives the third printing data, the second print trolley receives the fifth printing data, and the first print trolley and the second print trolley are respectively arranged at the two ends of the printing medium, and when the first print trolley is driven to move (scan) from right to left on the front side of the cross beam to print a PASS on the back side of the printing medium, the second print trolley is synchronously driven to move (scan) from left to right on the back side of the cross beam to print a PASS on the back side of the printing medium. After one PASS printing is completed, after the printing medium is controlled to move for a certain distance relative to the cross beam along the sub-scanning direction Y (or the stepping direction), the first printing trolley is controlled to move from left to right at the front side of the cross beam to print the next PASS on the front side of the printing medium, and the second printing trolley is driven to move from right to left at the rear side of the cross beam to print the next PASS on the back side of the printing medium, … … is controlled to scan the first printing trolley and the second printing trolley in a reciprocating mode until the image printing on the front side and the back side is completed. In each PASS printing, the height of the printing areas on the front and back sides is consistent, and the time and the position of the ink penetrating into the front and back sides of the printing medium are close, so that tension difference on the front and back sides caused by the fact that the ink penetrates successively is reduced, the influence of the tension difference on the printing effect is reduced, and the printing quality is improved.

In one embodiment, the image to be printed is a color image. Color images are often printed using C (cyan) M (magenta) Y (yellow) K (black) ink. The first print data obtained by rasterizing the image to be printed includes first black channel data, first cyan channel data, first magenta channel data, and first yellow channel data, and one example of the data format of the first print data is shown in fig. 4: the header is added with each row of data for each color channel. The color channel data for each row corresponds to the dot data corresponding to each pixel row of the printed image. The black channel data corresponding to the 0 th row of pixels in the front image corresponds to the black dot data of the 0 th row of pixels in the front image, and the cyan channel data corresponding to the 0 th row of pixels in the front image corresponds to the cyan dot data … … black cyan magenta yellow dots, which form a color image from a macroscopic view.

In the implementation of the present invention, the front and back printed images are identical and mirror images, and preferably, the expanding the first printed data to obtain the second printed data includes:

Inserting the second black channel data, the second cyan channel data, the second magenta channel data and the second yellow channel data of the ith row between the first black channel data, the first cyan channel data, the first magenta channel data and the first yellow channel data of the ith row and the (i+1) th row to obtain the second printing data;

Wherein i=0, 1,2, … … N-1, N is a natural number of 1 or more.

Specifically, as shown in fig. 5, the first black channel data, the first cyan channel data, the first magenta channel data, and the first yellow channel data of the 0 th row, the 1 st row … … th row, and the N-1 st row are copied to obtain the second black channel data, the second cyan channel data, the second magenta channel data, and the second yellow channel data of the corresponding rows, and the second black channel data, the second cyan channel data, the second magenta channel data, and the second yellow channel data of the i th row are inserted between the first black channel data, the first cyan channel data, the first magenta channel data, and the first yellow channel data of the i th row and the i+1 th row, respectively, to obtain the finally obtained expanded second print data.

Printing of the front and back side images can be performed based on the second print data. When printing, the second printing data is required to be split while being printed, the third printing data for printing the front side in the second printing data is extracted and distributed to the first printing trolley, and the fourth printing data for printing the back side is extracted and distributed to the second printing trolley. Preferably, the extracting the third print data and the fourth print data from the second print data includes:

And extracting second black channel data, second cyan channel data, second magenta channel data and second yellow channel data corresponding to the first black channel data, first cyan channel data, first magenta channel data and first yellow channel data line number in the third print data from the second print data as the fourth print data.

Specifically, when printing, the control software of the duplex inkjet printing device extracts the data of the corresponding number of lines from the second print data according to the data amount printed by each PASS and sends the data to the print carriage, if one PASS print data includes 1 line of each color channel data, then the first black channel data, the first cyan channel data, the first magenta channel data and the first yellow channel data of the 1 st line are firstly extracted from the second print data (denoted as third print data) and sent to the first print carriage, similarly, the second black channel data, the second cyan channel data, the second magenta channel data and the second yellow channel data (denoted as fourth print data) of the corresponding number of lines, namely the 1 st line, are extracted and sent to the second print carriage, and when the PASS is next, the first black channel data, the first cyan channel data, the first magenta channel data (denoted as third print data) of the 1 st line are extracted and sent to the first print carriage, and likewise, the second black channel data, the second magenta channel data and the second yellow channel data of the corresponding number of lines, namely the 1 st line are extracted and sent to the second print carriage.

Because the back image and the front image are mirror images, the fourth printing data is sent to the second printing trolley before being subjected to data processing to obtain fifth printing data. Preferably, the data processing of the fourth print data to obtain fifth print data includes:

If not, the mirror image printing data is the fifth printing data.

Specifically, the fourth print data and the third print data are identical before being subjected to data processing. Since mirror printing of a double-sided image is required, mirror processing of fourth print data is required, and data processing is generally performed in print control software of an upper computer of the double-sided inkjet printing apparatus. The end of each row of color channel data in the third print data and the fourth print data may contain blank data, the blank data does not drive the nozzle to jet ink, when the print control software performs mirror image processing on the fourth print data, the blank data is not subjected to mirror image processing on the blank data of each row, but the blank data is arranged at the end of the blank data after mirror image processing on the blank data of each row, if so processing results in an image printing result, as shown in fig. 6, a printing start point is set as a printing medium edge, after printing according to the third print data, the front image 11 starts to print at the right edge of the printing medium, due to the blank data at the end, part of blank pixels 13 (blank images) are arranged at the left edge, and after mirror image processing on the fourth print data, the blank data is still arranged at the end of each row, when the back image is printed, the front image 12 starts to print at the left edge of the printing medium, and the back image will have part of blank pixels 14 (blank images) at the right edge, so that the front image and the back image cannot be printed on the front image and the back image, if the printing medium is transparent, and the printing medium will not greatly affect the printing effect on the front and back image. For example, assuming that the width of the rasterized image is 6434 pixels, the number of bytes corresponding to each row of color channel data is 1612 bytes, variable dot printing (2 bit screening, printing can be performed by using large, medium and small dots), then 1 pixel needs 2 bits (2 bit) to represent, 1 byte (8 bit) can represent 4 pixels, each row of color channel data can store 1612×4=6448 pixels, that is, 6448-6434=14 pixels are blank pixels, and since 1 pixel occupies 2 bits, 14×2=28 bits of data are blank data, and if the printing precision is 360dpi,14/360×25.4=0.988 mm, that is, the front and back sides of the image cause an alignment error of nearly 1 mm.

In order to ensure the image printing quality, it is preferable to determine whether the end of each line of data in the fourth print data after the mirroring process includes blank data, and if so, the blank data needs to be moved to the front end of each line of data, and thus the fifth print data is obtained after the data processing. Illustratively, the fourth print data is as shown in fig. 7, with blank data 0 in the last byte, K-th byte. In practical situations, the blank data of the mirror image print data after mirror image processing is still at the end, namely the K-th byte, at this time, the blank data needs to be moved to the front end of the line data, and the final fifth print data is obtained. After data processing, as shown in fig. 8a, the front side image 12 blank pixels 13 and the back side image 12 blank pixels 14 are all at the left edge of the printing medium, and the front side image and the back side image are aligned.

It should be noted that mechanical errors (such as a carriage mounting error, a stepping error, etc.) in actual production may inevitably result in a slight misalignment of the front and back images, as shown in fig. 9, such as a pair Ji Piancha E1 in the X direction (hereinafter referred to as a vertical pair Ji Piancha), a pair Ji Piancha E2 in the Y direction (hereinafter referred to as a horizontal misalignment), or both of the misalignment. In some precision demanding applications, even fine alignment deviations can affect product quality and lead to reduced customer satisfaction.

After the fourth print data is processed to obtain the fifth print data, in order to ensure accurate alignment of the images on the front and back sides in actual printing, the first print trolley and the second print trolley are firstly controlled to print test images according to the third print data and the fifth print data, the alignment condition of the front and back sides is determined according to the test images, and the third print data and the fifth print data are further adjusted according to the alignment condition. In one embodiment, after the fifth print data is acquired, further comprising:

and inserting or deleting a plurality of blank data at the front end of each row of data in the third printing data and/or the fifth printing data according to the vertical alignment deviation.

Specifically, the third print data and the fifth print data may be one PASS data or more PASS data in the overall print data, and the third print data and the fifth print data are used to print a test image to determine whether there is a vertical alignment deviation and a size thereof, and blank data is inserted or deleted in the third print data or the fifth print data in an actual print process according to the vertical alignment deviation to perform correction. For example, in the double-sided printing, each side of the printing mode is 2PASS printing, the printing precision is 360dpi x 360dpi, when the double-sided printing of 2PASS data is started, first two sides of the printing mode are printed to obtain a first test image 91 and a second test image 92 respectively, as shown in fig. 9, assuming that the distance between the first test image 91 on the front side and the left edge of the printing medium (or the left end initial printing position) is 1.2mm, the distance between the second test image 92 on the back side and the left edge of the printing medium (or the left end initial printing position) is 1mm, then a vertical alignment deviation is obtained according to the first test image and the second test image, as shown in E1 of fig. 9, and is 0.2mm, the number of blank data to be inserted or deleted is 3 according to the printing precision and the alignment deviation, then in the actual printing process, 3 blank data can be deleted at the front end of each line of data in order to correct the alignment deviation, or 3 blank data can be deleted at the front end of each line of data in the fifth printing data, or the front end of each line of blank data in the fifth printing data, and the blank data of each line of 1 blank data in the fifth printing data can be deleted at the front end of each line of blank data; if the front ends of the third printing data and the fifth printing data have no blank data, the alignment deviation can be corrected by inserting the blank data. By way of example, assuming that the first test image 91 of the front side is 0mm from the left edge of the printing medium (or the left end start printing position) and the second test image 92 of the back side is 0.2mm from the left edge of the printing medium (or the left end start printing position), the misalignment is corrected by inserting 3 blank data at the front end of the third print data or 3 blank data at the front end of the fifth print data.

In one embodiment, when the number of blank data to be inserted or deleted acquired according to the horizontal alignment deviation is smaller than 1, the alignment deviation may be corrected by adjusting the ink value corresponding to the non-blank data at the beginning and end of each line of data, for example, assuming that the vertical alignment deviation E1 acquired in fig. 9 is 0.05, and the number of blank data to be inserted or deleted is 0.7 according to the printing precision and the vertical alignment deviation, at this time, the ink amount of the non-blank data at the beginning and end of each line of data in the third print data may be adjusted, for example, the ink amount of the first non-blank data in each line of data may be increased and the ink amount of the last non-blank data may be decreased, so as to decrease the vertical alignment deviation.

In one embodiment, if the horizontal alignment deviation is detected by the first test image and the second test image, after controlling the first print carriage and the second print carriage to print the first test image and the second test image on the front and back sides of the print medium according to the third print data and the fifth print data, respectively, the method further comprises:

And inserting or deleting a plurality of rows of blank data in the third printing data and/or the fifth printing data according to the horizontal alignment deviation. As an example, as shown in fig. 9, assuming that the horizontal alignment deviation E2 of the first test image 91 and the second test image 92 is detected to be 0.2mm, the number of lines of blank data to be inserted or deleted is 3 lines according to the printing accuracy and the horizontal alignment deviation, and then in the actual printing process, 3 lines of blank data may be inserted in front of the 0 th line of data in the third print data (equivalent to shifting up the front image by 0.2mm in the Y direction, or, if the front data (in front of the 0 th line of data) in the fifth print data includes a plurality of lines of data as blank data, 3 lines of blank data may be deleted, or, correction may be performed by inserting 2 lines of blank data in front of the third print data and deleting 1 line of blank data in the fifth line of print data.

In one embodiment, when the number of lines of blank data to be inserted or deleted acquired according to the horizontal alignment deviation is less than 1, the modification may be performed by adjusting the ink value corresponding to the data. For example, when the horizontal alignment deviation E2 shown in fig. 9 is 0.05mm, the number of blank data lines to be adjusted is 0.7 lines, at this time, the amount of ink corresponding to the 0 th line of data (corresponding to the lower side of the image) of the third print data may be reduced, and the amount of ink corresponding to the last line of data (corresponding to the upper side of the image) of the third print data may be increased to reduce the horizontal alignment deviation of the front-back image.

In one embodiment, the print image positions on both sides of the print medium are centered, and the initial print positions of the print image need to be calculated, that is, the initial print positions of the first print carriage and the second print carriage need to be acquired before printing. Preferably, acquiring the starting print positions of the first print carriage and the second print carriage includes:

Specifically, the maximum scanning width of the first print carriage in the main scanning direction X is the maximum width of an image that can be printed when the first print carriage moves in the main scanning direction (also referred to as a machine width in the industry), and is denoted as a first width, the width of an image to be printed on a print medium, that is, the width of an image to be printed in the main scanning direction, is denoted as a second width, and the initial printing positions of the first print carriage and the second print carriage can be calculated from the first width and the second width. Illustratively, the first width is 2000mm, the second width is 1000, (2000-1000)/2=500 mm, and when printing, the first print carriage starts to move from right to left in the main scanning direction from the printing origin at the right end of the beam by 500mm, and similarly, the second print carriage starts to move from left to right in the main scanning direction from the printing origin at the right end of the beam by 500 mm. Preferably, the main board control system of the lower computer of the inkjet printing device performs automatic centering processing of image printing according to the calculation method, after the first width and the second width are input, the control system automatically calculates initial printing positions of the first printing trolley and the second printing trolley according to the data, and controls the first printing trolley and the second printing trolley to start spraying ink at the initial printing positions for image printing. As shown in fig. 9, an exemplary diagram of automatic centering printing in an embodiment of the present invention. The control system automatically calculates a start print position 17 for the front image 15 and a start print position 18 for the back image 16 based on the first width and the second width such that the front image and the back image are printed centrally.

In practical application, due to different printing medium materials, the absorbing or carrying capacity of the printing medium is different, and because the printing medium needs to be printed on the front side and the back side, if the quantity of the ink sprayed by the printing trolley is too large, the ink on the front side and the back side is mutually permeated into the opposite images, so that the imaging effect is seriously influenced, and the final printing quality is influenced. In one embodiment, to mitigate the effects of interpenetration between the front and back side inks, to enhance the printing on the front and back sides, the amount of ink in the print data is adjusted by determining the preferred value of ink that can be carried or absorbed by the front and back sides of the print medium. Preferably, the first print data is composed of dot data, and before expanding the first print data to obtain the second print data, the method further includes:

acquiring the total ink quantity corresponding to the first printing data;

Specifically, the preferred values of the amounts of ink carried by the front and back sides of the print medium, i.e., the first preferred amount of ink and the second preferred amount of ink, may be determined by: and (3) acquiring the ink quantity of the ink when the ink is ejected to the front side of the printing medium to form an image and the image effect reaches the preset requirement (such as the image concentration, the color saturation and the like of the front side image reach the requirement but the ink does not permeate to the back side), recording the ink quantity at the moment as a first preferred ink quantity, and acquiring a second preferred ink quantity by the same method. If the material of the front and back sides of the print medium are the same, the first preferred ink amount and the second preferred ink amount are generally the same.

The first print data is image dot matrix data after rasterizing the image to be printed, and the image dot matrix data is tensor data with two dimensions or higher dimensions, and consists of dot data. Each dot data is used to characterize the ink output of a corresponding nozzle. Taking 2-bit screening (or rasterizing) as an example, the dot data includes dot data 00, dot data 01, dot data 10, and dot data 11, and for convenience of description, the dot data 00 is noted as null dot data, the dot data 01 is noted as small dot data, the dot data 10 is noted as medium dot data, and the dot data 11 is noted as large dot data. The ink amounts of the large dot data, the medium dot data, and the small dot data at the time of printing are different, and by way of example, the ink amount of the large dot data is set to 10PL (the first ink amount is 10 PL), the ink amount of the medium dot data is 7PL (the second ink amount is 7 PL), the ink amount of the small dot data is 5PL (the third ink amount is 5 PL), if a certain print data (dot data) in the first print data is 11, the ink amount thereof is the large dot, the ink amount thereof to be ejected at the time of printing is 10PL, if a certain print data (dot data) in the first print data is 10, the ink amount thereof to be the medium dot … …, and the first ink amount, the second ink amount, and the third ink amount may be set according to the actual print conditions, with the above 10PL, 7PL, and 5PL being just examples. The total ink quantity corresponding to the first printing data can be calculated according to the ink quantity corresponding to the point data. The first printing data is data of one side (the front side or the back side) of the printing medium, whether the ink quantity to be ejected is larger than the preferred value of the ink quantity borne or absorbed by the front side or the back side of the printing medium or not can be known according to the total ink quantity, the first preferred ink quantity and the second preferred ink quantity, and if so, the ink quantity corresponding to each point data in the first printing data can be correspondingly adjusted, so that the ejected ink quantity cannot exceed the preferred value of the ink quantity borne by the front side or the back side of the printing medium.

Preferably, the adjusting the ink value corresponding to the dot data according to the total ink amount, the first preferred ink amount, and the second preferred ink amount includes:

Specifically, in one embodiment, if the materials on both sides of the front surface of the print medium are the same, and the first preferred ink amount and the second preferred ink amount are the same, it is only necessary to determine whether the first difference between the first preferred ink amount and the total ink amount or the second difference between the second preferred ink amount and the total ink amount is greater than a preset threshold, where the preset threshold may be determined according to the actual application situation. If it exceeds, it may cause the ink on both sides to mutually permeate, and the ink amount of the ink to be ejected thereon needs to be reduced, and accordingly, the first print data needs to be adjusted. For example, after the first difference or the second difference is obtained, an ink amount adjustment value for reducing the ink amount corresponding to the first print data may be known, and any one or more of the ink amount of the large dot data (first ink amount), the ink amount of the medium dot data (second ink amount), or the ink amount of the small dot data (third ink amount) may be adjusted according to the ink amount adjustment value. For example, if the ink volume adjustment value is calculated to be 100PL, and the first print data includes 100 large ink dots, 100 small ink dots, and 200 small ink dots, only the ink volume of the 100 large ink dots may be adjusted, for example, 10PL is adjusted to 9PL, so that the total ink volume corresponding to the first print data is reduced by 100PL. And when the second printing data is obtained by expanding the first printing data, and the third printing data and the fourth printing data (the fifth printing data is obtained after data processing) are extracted from the second printing data to perform front-back printing, the ink quantity corresponding to the large ink point data in the third printing data and the fifth printing data is correspondingly reduced, so that the influence of the mutual permeation of the front-back ink when the ink quantity is overlarge is effectively reduced.

In another embodiment, if the materials corresponding to the front and back sides of the print medium are different, the first preferred ink amount and the second preferred ink amount are different, and at this time, the first preferred ink amount and the second preferred ink amount need to be compared with the total ink amount of the first print data respectively to obtain different first difference values and second difference values, and different ink amount adjustment values of the front and back sides are obtained according to the first difference values and the second difference values, and the first ink amount adjustment value and the second ink amount adjustment value are respectively provided, when the front image is printed, that is, when the front image is printed according to the third print data, any one or more of the first ink amount, which is the ink amount of the large ink dot data, the second ink amount, which is the ink amount of the medium ink dot data, and the third ink amount, which is the ink amount of the small ink dot data, is adjusted according to the first ink amount adjustment value, and when the reverse image printing is performed, that is, when the printing is performed according to the fifth printing data, any one or more of the first ink amount, which is the ink amount of the large ink dot data, the second ink amount, which is the ink amount of the medium ink dot data, and the third ink amount, which is the ink amount of the small ink dot data, is adjusted according to the second ink amount adjustment value, so that the influence of the mutual permeation of the front and back inks when the ink amount is too large is effectively reduced.

In summary, according to the duplex inkjet printing method provided by the embodiment of the invention, the first print carriage and the second print carriage are driven to synchronously move in opposite directions or in opposite directions at the same printing height based on one driving mechanism to realize simultaneous printing of the front and back sides of the printing medium. The double-sided ink-jet printing data processing method provided by the invention is simple and efficient, can better meet the requirement of double-sided printing, improves the printing quality and efficiency, and improves the user satisfaction.

Example two

Referring to fig. 10, according to the first embodiment, the embodiment of the invention provides a duplex inkjet printing apparatus 200, the apparatus 200 includes:

the data acquisition module 201 is configured to acquire an image to be printed, and perform rasterization processing on the image to be printed to obtain first print data;

A data expansion module 202, configured to expand the first print data to obtain second print data;

A data extraction module 203 for extracting third print data and fourth print data from the second print data, respectively;

A data processing module 204, configured to perform data processing on the fourth print data to obtain fifth print data;

The printing module 205 is configured to send the third print data and the fifth print data to the first print carriage and the second print carriage, respectively, and drive the first print carriage and the second print carriage to move in opposite directions or in opposite directions at the same printing height synchronously, and jet ink to the front and back sides of the print medium to form images.

Preferably, the first print data includes first black channel data, first cyan channel data, first magenta channel data, and first yellow channel data each having N rows, and the data expansion module 202 includes:

A copying unit, configured to copy, in the first print data, first black channel data, first cyan channel data, first magenta channel data, and first yellow channel data of an ith row, respectively, to obtain second black channel data, second cyan channel data, second magenta channel data, and second yellow channel data of the ith row;

An inserting unit configured to insert second black channel data, second cyan channel data, second magenta channel data, and second yellow channel data of an i-th line between first black channel data, first cyan channel data, first magenta channel data, and first yellow channel data of the i-th line and i+1th line, to obtain the second print data;

Where i=0, 1,2, … … N-1.

Preferably, the data extraction unit includes:

A first extracting unit configured to extract the first black channel data, the first cyan channel data, the first magenta channel data, and the first yellow channel data from the second print data in order of number of lines as the third print data;

And a second extraction unit configured to extract, from the second print data, second black channel data, second cyan channel data, second magenta channel data, and second yellow channel data corresponding to the number of lines of first black channel data, first cyan channel data, first magenta channel data, and first yellow channel data in the third print data as the fourth print data.

Preferably, the data processing module 204 includes:

The mirror image processing unit is used for carrying out mirror image processing on the fourth printing data to obtain mirror image printing data;

A judging unit for judging whether the tail of each line of data in the mirror image printing data contains blank data;

The first acquisition unit is used for placing the blank data at the front end of each row of data to obtain the fifth printing data if the blank data are the blank data;

And the second acquisition unit is used for acquiring the mirror image printing data, namely the fifth printing data, if not.

Preferably, the apparatus further comprises:

A first width acquisition module, configured to acquire a maximum scanning width of the first print carriage in a main scanning direction, which is denoted as a first width;

A second width acquisition module, configured to acquire a width of the image to be printed in the main scanning direction, and record the width as a second width;

And the initial printing position acquisition module is used for acquiring initial printing positions of the first printing trolley and the second printing trolley according to the first width and the second width.

Preferably, the apparatus further comprises:

the total module acquisition module is used for acquiring the total ink quantity corresponding to the first printing data;

A preferred ink amount acquiring ink amounts for determining preferred values of the amounts of ink carried by the front and back sides of the print medium, respectively, noted as a first preferred ink amount and a second preferred ink amount;

And the adjusting module is used for adjusting the ink value corresponding to the dot data according to the total ink quantity, the first preferred ink quantity and the second preferred ink quantity.

Preferably, the dot data includes large dot data, medium dot data, and small dot data, and the corresponding ink amounts are recorded as a first ink amount, a second ink amount, and a third ink amount, respectively, where the first ink amount > the second ink amount > the third ink amount, and the adjustment module includes:

A comparison unit configured to determine whether a first difference between the total ink amount and the first preferred ink amount is equal to or greater than a preset threshold value and/or whether a second difference between the total ink amount and the second preferred ink amount is equal to or greater than the preset threshold value;

The ink quantity adjusting value obtaining unit is used for obtaining an ink quantity adjusting value according to the first difference value and/or the second difference value if yes;

an adjustment unit configured to adjust any one or more of the first ink amount, the second ink amount, and the third ink amount according to the ink amount adjustment value.

In summary, according to the double-sided inkjet printing device provided by the embodiment of the invention, the first printing trolley and the second printing trolley are driven to synchronously move in opposite directions or in opposite directions from two ends of the printing medium respectively at the same printing height based on one driving mechanism, so that the front and back sides of the printing medium can be printed simultaneously. In addition, the data processing mode in printing in the method is simple and efficient, can better meet the requirement of double-sided ink-jet printing, improves the printing quality and efficiency, and improves the user satisfaction.

Example III

In addition, the double-sided inkjet printing method of the embodiment of the present invention may be implemented by a double-sided inkjet printing apparatus. As shown in fig. 1 or fig. 2, the duplex inkjet printing apparatus includes a first print carriage and a second print carriage, a print medium is vertically disposed between the first print carriage and the second print carriage, the first print carriage and the second print carriage are reciprocally movable in a main scanning direction by driving of the same driving mechanism, the first print carriage is configured to eject ink to a front side of the print medium to form an image, and the second print carriage is configured to eject ink to a back side of the print medium to form an image. In addition, the inkjet printing device further includes a host computer integrated with a rasterization processor and printing control software, and fig. 11 shows a schematic hardware structure of a control system of the dual-sided inkjet printing device according to an embodiment of the present invention.

The dual sided inkjet printing device control system may include a processor 301 and a memory 302 storing computer program instructions.

In particular, the processor 301 may include a Central Processing Unit (CPU), or an Application SPECIFIC INTEGRATED Circuit (ASIC), or may be configured as one or more integrated circuits that implement embodiments of the present invention.

Memory 302 may include mass storage for data or instructions. By way of example, and not limitation, memory 302 may comprise a hard disk drive (HARD DISK DRIVE, HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or universal serial bus (Universal Serial Bus, USB) drive, or a combination of two or more of the foregoing. Memory 302 may include removable or non-removable (or fixed) media, where appropriate. Memory 302 may be internal or external to the data processing apparatus, where appropriate. In a particular embodiment, the memory 302 is a non-volatile solid-state memory. In particular embodiments, memory 302 includes Read Only Memory (ROM). The ROM may be mask programmed ROM, programmable ROM (PROM), erasable PROM (EPROM), electrically Erasable PROM (EEPROM), electrically rewritable ROM (EAROM), or flash memory, or a combination of two or more of these, where appropriate.

The processor 301 implements any of the duplex inkjet printing methods of the above-described embodiments by reading and executing the computer program instructions stored in the memory 302.

In one example, the dual-sided inkjet printing device control system can also include a communication interface 303 and a bus 310. As shown in fig. 11, the processor 301, the memory 302, and the communication interface 303 are connected to each other by a bus 310 and perform communication with each other.

The communication interface 303 is mainly used to implement communication between each module, device, unit and/or apparatus in the embodiment of the present invention.

Bus 310 includes hardware, software, or both, that couple components of the dual sided inkjet printing device control system to each other. By way of example, and not limitation, bus 310 may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an infiniband interconnect, a Low Pin Count (LPC) bus, a memory bus, a micro channel architecture (MCa) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a video electronics standards association local (VLB) bus, or other suitable bus, or a combination of two or more of the above. Bus 310 may include one or more buses, where appropriate. Although embodiments of the invention have been described and illustrated with respect to a particular bus, the invention contemplates any suitable bus or interconnect.

Example IV

In addition, in combination with the duplex inkjet printing method in the above embodiment, the embodiment of the present invention may be implemented by providing a computer-readable storage medium. The computer readable storage medium has stored thereon computer program instructions; the computer program instructions, when executed by the processor 301, implement any of the two-sided inkjet printing methods of the above embodiments.

It should be understood that the invention is not limited to the particular arrangements and instrumentality described above and shown in the drawings. For the sake of brevity, a detailed description of known methods is omitted here. In the above embodiments, several specific steps are described and shown as examples. The method processes of the present invention are not limited to the specific steps described and shown, but various changes, modifications and additions, or the order between steps may be made by those skilled in the art after appreciating the spirit of the present invention.

The functional blocks shown in the above-described structural block diagrams may be implemented in hardware, software, firmware, or a combination thereof. When implemented in hardware, it may be, for example, an electronic circuit, an Application Specific Integrated Circuit (ASIC), suitable firmware, a plug-in, a function card, or the like. When implemented in software, the elements of the invention are the programs or code segments used to perform the required tasks. The program or code segments may be stored in a machine readable medium or transmitted over transmission media or communication links by a data signal carried in a carrier wave. A "machine-readable medium" may include any medium that can store or transfer information. Examples of machine-readable media include electronic circuitry, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio Frequency (RF) links, and the like. The code segments may be downloaded via computer networks such as the internet, intranets, etc.

It should also be noted that the exemplary embodiments mentioned in this disclosure describe some methods or systems based on a series of steps or devices. The present invention is not limited to the order of the above-described steps, that is, the steps may be performed in the order mentioned in the embodiments, or may be performed in a different order from the order in the embodiments, or several steps may be performed simultaneously.

In the foregoing, only the specific embodiments of the present invention are described, and it will be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the systems, modules and units described above may refer to the corresponding processes in the foregoing method embodiments, which are not repeated herein. It should be understood that the scope of the present invention is not limited thereto, and any equivalent modifications or substitutions can be easily made by those skilled in the art within the technical scope of the present invention, and they should be included in the scope of the present invention.

Claims

1. A duplex inkjet printing method, characterized in that the method is applied to a duplex inkjet printing apparatus including a first print carriage and a second print carriage, a print medium being vertically disposed between the first print carriage and the second print carriage, the first print carriage and the second print carriage being reciprocally movable in a main scanning direction under the drive of the same drive mechanism, the first print carriage being for ejecting ink to a front side of the print medium to form an image, the second print carriage being for ejecting ink to a back side of the print medium to form an image, the method comprising:

Expanding the first printing data to obtain second printing data;

2. The duplex inkjet printing method of claim 1 wherein the first print data includes first black channel data, first cyan channel data, first magenta channel data, and first yellow channel data each having N rows, and expanding the first print data to obtain second print data includes:

Wherein i=0, 1,2, … … N-1, N is a natural number of 1 or more.

3. The duplex inkjet printing method according to claim 2, wherein the extracting third print data and fourth print data from the second print data respectively includes:

4. The duplex inkjet printing method according to claim 1, wherein the performing data processing on the fourth print data to obtain fifth print data includes:

If not, the mirror image printing data is the fifth printing data.

5. The duplex inkjet printing direction as in claim 4 further comprising, after the data processing of the fourth print data to obtain fifth print data:

And/or:

6. The duplex inkjet printing method according to claim 1, wherein before the third print data and the fifth print data are sent to the first print carriage and the second print carriage, respectively, the first print carriage and the second print carriage are driven to synchronously move toward each other at the same print height, respectively, from both ends of the print medium and to eject ink to both sides of the print medium to form images, further comprising:

7. The duplex inkjet printing method according to claim 1, wherein the first print data is composed of dot data, and further comprising, before the expanding the first print data to obtain second print data:

acquiring the total ink quantity corresponding to the first printing data;

8. The duplex inkjet printing method according to claim 7, wherein the dot data includes large dot data, medium dot data, and small dot data, and the corresponding ink amounts thereof are recorded as a first ink amount, a second ink amount, and a third ink amount, respectively, wherein the first ink amount > the second ink amount > the third ink amount, and the adjusting the ink value corresponding to the dot data based on the total ink amount and the first and second preferred ink amounts includes:

9. A duplex inkjet printing apparatus, the apparatus being applied to duplex inkjet printing equipment, wherein the duplex inkjet printing equipment includes a first print dolly and a second print dolly, a print medium is vertically disposed between the first print dolly and the second print dolly, the first print dolly and the second print dolly are reciprocally movable in a main scanning direction under the drive of the same drive mechanism, the first print dolly is for ejecting ink to a front side of the print medium to form an image, and the second print dolly is for ejecting ink to a back side of the print medium to form an image, the apparatus comprising:

10. A duplex inkjet printing apparatus, wherein the duplex inkjet printing apparatus includes a first print carriage and a second print carriage, a print medium being vertically disposed between the first print carriage and the second print carriage, the first print carriage and the second print carriage being reciprocally movable in a main scanning direction by driving of a same driving mechanism, the first print carriage being for ejecting ink to a front side of the print medium to form an image, the second print carriage being for ejecting ink to a back side of the print medium to form an image; the double-sided inkjet printing apparatus further includes: at least one processor, at least one memory, and computer program instructions stored in the memory, which when executed by the processor, implement the method of any one of claims 1-8.