JP2015128844A - Image formation device and image formation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform oblique printing with a method easier than a prior art requiring rendering processing used in printing with a normal scan method and rendering processing for oblique printing.SOLUTION: An image formation device moves an ink jet (IJ) head at constant speed on the basis of input (S101) original image data and generates data for discharge control used in printing with a normal scan method of printing a reproduction image on a stationary sheet with rendering processing (S103), calculates an oblique coefficient for relatively moving the IJ head obliquely with respect to the sheet (performed at constant speed on the basis of sheet conveyance and the movement of the IJ head), and sends the oblique coefficient with the data for discharge control obtained in the former stage to a head controller for controlling discharge of the IJ head (S106). The head controller adjusts the received data for discharge control for oblique printing on the basis of the oblique coefficient, and controls discharge of the IJ head at the timing matching an oblique printing operation (S107).

Description

The present invention is based on data processed from an original image by moving an inkjet (hereinafter referred to as “IJ”) head in which a plurality of nozzles are arranged at a constant speed in the main scanning direction while conveying the paper at a constant speed in the sub-scanning direction. The present invention relates to an image forming apparatus that controls an ejection operation of an IJ head and performs oblique printing.
More specifically, an image obtained by applying data obtained by processing an original image in a normal scanning method using the IJ head to stationary paper, which has been conventionally used, to oblique printing using the main and sub simultaneous scanning methods. The present invention relates to a forming apparatus. The present invention also relates to an image forming method including a step of making it possible to apply the above-described image processing conventionally employed in a normal scanning method to oblique printing.

Conventionally, “printing noise and vibration” has been cited as one of the major problems to be solved in a printer that records an image on a recording medium (hereinafter also referred to as “paper”) with ink or the like by a scanning method. .
In a serial type IJ (inkjet) printer, noise and vibration are generated by an operation of motor control necessary for printing.
There are mainly two motor control operations during printing. One is based on main scanning motor control that moves the carriage on which the IJ head that ejects ink droplets is mounted. The other is based on sub-scanning motor control for conveying a sheet as a recording medium.

Other motor control operations include ink supply motor control for supplying ink to the IJ head placed on the carriage and maintenance motor control for performing maintenance on the discharge nozzles of the IJ head placed on the carriage.
However, the motor control that affects “noise and vibration during printing” is the motor control of the main scanning and sub-scanning. Among these, “noise / vibration” by the sub-scanning motor control is dominant, and there is a higher demand for improving the sub-scanning motor control in order to reduce the noise / vibration.

Therefore, from the idea of reducing noise and vibration by eliminating sudden acceleration / deceleration and high-speed motor control, which is the source of noise and vibration in the sub-scanning direction of the above-mentioned prior art, a sub-scanning motor that transports paper during printing is used. A “diagonal printing” method has been proposed which always operates at a constant low speed. As a prior art by this method, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2004-338215) can be cited.
In the proposed oblique printing method, the sub-scanning motor is operated at a constant low speed to convey the paper, and at the same time, in the main scanning direction, the main scanning motor is operated at a constant speed as in the prior art. Moving. In this way, by operating the main and sub scanning motors simultaneously, oblique printing is performed by the IJ head that moves obliquely with respect to the paper, that is, the pixel column lines formed by the pixels that are arranged in the dot-sequential manner in the main scanning are formed. Printing is performed in an inclined state with respect to the main scanning direction.

Here, a printer that performs a printing operation by a conventional oblique printing method will be described in more detail.
FIG. 2 is a diagram showing a configuration of a print control system of a printer that enables conventional oblique printing. The configuration of the print control system in FIG. 2 is common to the control system according to an embodiment of the present invention to be described later. Therefore, the description below will be referred to and the description will be simplified here.
When performing oblique printing, the main scanning and sub-scanning motors are controlled so that the IJ head 6 moves linearly and obliquely at a constant speed with respect to the paper in the printing area, and the IJ head 6 is moved. Print control is performed to eject ink droplets synchronously.
As shown in FIG. 2, the SoC (System On Chip) 2 provided on the CTL board 1 includes an IJ head 6 that ejects ink droplets, a head motor 8 that is a main scanning motor, and a sub-control system that performs this printing operation. A system configuration for centrally controlling the paper conveyance motor 10 which is a scanning motor is formed.

FIG. 19 is a diagram for explaining an oblique printing operation in the prior art.
The IJ head 6 ejects ink droplets while reciprocating in the main scanning direction orthogonal to the sub-scanning direction for transporting the paper.
In the oblique printing method, since the paper is always conveyed during printing, the printing area of the IJ head 6 passing over the paper is slanted as shown in FIG. If the IJ head 6 has a nozzle row in which nozzles are arranged at predetermined intervals in the sub-scanning direction, the pixel row line of each pixel recorded obliquely on the paper is forward (see FIG. 19B). (A) (position A → position B direction), the slope is reversed on the return path (position B → position C direction in FIG. 19 (A)).

Further, the IJ head 6 is a multi-pass printing system in which the head passes the same portion of the paper surface a plurality of times by scanning in the forward path and the backward path, and the reciprocating paths overlap as shown in FIG.
In the multi-pass printing method, it is required to always make the overlapping area in a plurality of passes uniform.
The example of FIG. 19 is a two-pass printing method. In the two-pass printing, in order to always make the overlapping area uniform, each scanning path (position A → position B, position B → position C, position C → position D...) Of the IJ head 6 in the sub-scanning direction. The moving distance is based on a specification that advances a distance that is half (1/2) the length of the nozzle row of the IJ head 6 in the sub-scanning direction.

It is a knowledge obtained so far that when oblique printing is performed by the above-described scanning method, an image formed in a portion where the forward and backward scanning by the IJ head 6 overlap is generated.
FIG. 20 is a diagram illustrating a landing state of ink droplets in a portion where scanning is overlapped in the forward pass and the return pass in the conventional oblique printing.
In oblique printing, the paper is always transported in the sub-scanning direction during printing, so when looking closely at the forward ink drop ("black circle" in FIG. 20) and the backward ink drop ("grey circle"), FIG. As shown in the figure, the landing positions of the same pixels that should be essentially matched are shifted in the sub-scanning direction. Among the ink droplets where the forward and backward scans overlap, there are overlapping portions as in the circled area in the figure, but there are more portions where they do not overlap. This displacement of the landing positions of ink droplets causes image disturbance.

In the oblique printing performed by the main and sub simultaneous scanning methods, the inclination of the pixel row lines of the pixels arranged and arranged dot-sequentially in the main scanning by the nozzles arranged in the sub scanning direction depends on the main scanning speed and the sub scanning speed. Determined. In the forward path and the backward path, the absolute value of the main scanning speed does not change even if the direction is reversed, so that the pixel column lines are inclined in the opposite direction but with the same inclination. Further, the interval between the pixels on the pixel line is determined by the controllable ink droplet ejection timing.
Therefore, in the forward and backward scans by the heads having nozzle rows arranged at regular intervals in the sub-scan direction, the scans overlap theoretically by matching the main scan and sub-scan speeds with the ink droplet ejection timing. Printing should be able to be performed without causing the landing position deviation in the portion.

However, in reality, since each device has its own characteristics, even if it operates according to the same theoretical value, scanning of diagonal printing in which the pixel column line has an ideal inclination is not performed in each of forward and backward scanning. An error occurs in the tilt. As a result, the landing position shift of the ink droplet appears as shown in FIG.
Since this landing position deviation correction has an operation condition peculiar to the oblique printing by the main and sub simultaneous scanning systems, the landing position deviation correction technique in the conventional normal scanning system without sub scanning cannot be directly applied.
Therefore, in order to ensure the same image accuracy as that of a printer that performs serial printing using a normal scanning method that does not perform oblique printing, and to maintain high image quality, it is necessary to correct this shift appropriately. Do not look.

By the way, the serial type ink jet printer performs a process of creating, from the original image data, nozzle discharge control data used for image formation corresponding to the movement of the IJ head 6 that performs main scanning as a rendering process.
When rendering processing is performed to form a reproduced image of the original image on a stationary sheet and the obtained data is used for oblique printing, the sheet is always conveyed in the sub-scanning direction in oblique printing, so the original image is inclined on the sheet. It is printed in the state.
The conventional technique proposed to solve this problem is a method of performing image processing with correction in rendering processing so that the original image is reproduced on the paper in the original state even in oblique printing ( Patent Document 1).

FIG. 21 is a diagram showing a control flow of the printing operation by the conventional oblique printing method. This control flow will be described as a control operation in oblique printing performed by the printing control system of the printer previously described with reference to FIG.
According to the control flow of FIG. 21, when a status change corresponding to a print request occurs in the printer, the SoC 2 computer starts this control flow.
After startup, first, image data to be printed is input from an external device such as a PC (personal computer), a smart device, a USB (Universal Serial Bus) memory, an SD card, or the like (step S1).
The input image data is subjected to data processing (compression / decompression / rotation / magnification, etc.) necessary for making it adaptable to IJ rendering in the subsequent stage, and then temporarily stored (expanded) in a memory such as DRAM 4 (Step S2).

Thereafter, as the IJ rendering, the arrangement of the nozzle rows of the IJ head 6 and the reciprocating operation direction are taken into consideration, and the order of the image data is arranged in the order of actually ejecting ink droplets from the nozzles of the IJ head 6 (step S3). It is stored again in the memory (step S4).
Next, as a processing procedure of the oblique printing method, in addition to the processing performed in step S3 which is a normal IJ rendering processing for forming an image on a stationary sheet, oblique image IJ rendering is performed (step S5). In this process, the image data obtained in the IJ rendering process (step S3) used when an image is formed on a stationary sheet by a normal scanning method is used as it is for oblique printing. It is a rendering process given to image data.

The image data obtained by the IJ rendering for the oblique image in step S5 is stored in the memory (step S6).
The image data used for the oblique printing stored in the memory in step S6 is transferred to HEADCTL 2b that controls the head driver 5 that drives the IJ head 6 (step S7).
The HEADCTL 2b that receives the transferred image data used for the oblique printing generates a control signal for driving all the nozzles of the IJ head 6 in accordance with the main scanning encoder signal based on the image data, and outputs the control signal to the head driver 5. The head driver 5 drives the IJ head 6 in accordance with the input control signal, and prints by ejecting ink droplets from the nozzles (step S8).
By repeating the operations in steps S7 and S8, an image is formed on the paper.
By performing this control flow, the image data is formed obliquely with an inclination opposite to the direction, so that even if the image data is ejected while transporting the paper, the printed image that actually appears on the paper is obliquely formed. The image is normally formed.

However, in the control flow described above, rendering processing of image data used for oblique printing that is secondarily performed on data after normal IJ rendering processing requires a higher level of technology than normal IJ rendering processing. This is because the rendering process for oblique printing has many variation parameters such as the speed in the sub-scanning direction, the speed in the main scanning direction, and the ink ejection time.
Note that the correction for the minute landing position deviation generated in the sub-scanning direction in the oblique printing described above with reference to FIG. 20 is left unsolved in the conventional oblique printing technology including Patent Document 1. It is a problem.
As described above, in the prior art, in order to cope with oblique printing, a high-level image processing means is newly required for processing image data, and the development man-hour is increased. Therefore, problems such as an increase in development burden and an increase in memory capacity in terms of processing means lead to an increase in product cost.

  The object of the present invention is to compare with the conventional technique in which IJ rendering processing for oblique printing needs to be performed in addition to rendering processing used when printing is performed on a stationary sheet by a normal scanning method performed only by main scanning of the IJ head. It is to enable oblique printing by a simpler method.

  The present invention has conveying means for conveying a recording medium in the sub-scanning direction, and moving means for moving in the main scanning direction an inkjet head having nozzle rows in which nozzles for ejecting ink droplets are arranged at regular intervals in the sub-scanning direction The nozzles are operated in synchronization with the movement of the inkjet head by the ejection control data generated based on the original image data, and are arranged in the main and sub scanning directions on the recording medium by the ink ejected from the nozzles. An image forming apparatus for printing a pixel group, a head movement control unit for controlling the moving unit to move the inkjet head at a predetermined constant speed during a printing period, and a predetermined constant level for the recording medium during the printing period. Recording medium conveyance control means for controlling the conveyance means so that it can carry out oblique printing by conveying at a speed, and a configuration arranged in the main and sub scanning directions The head movement control means and the recording medium conveyance control means are operated in accordance with the relationship of the recording medium conveyance speed with respect to the movement speed of the inkjet head determined to print the pixel group, and each of the pixel groups constituting the pixel group in the printing period An oblique printing operation control means for operating the nozzles of the inkjet head based on ejection control data for oblique printing used for the pixels, and an original image on the stationary recording medium by controlling the movement of the inkjet head by the head movement control means. As the ejection control data used for printing the reproduced image, image processing means for creating a data group of pixels arranged in the main and sub scanning directions from the original image data, and the image processing means Discharge for oblique printing used in the oblique printing operation control means for the ejection control data An image forming apparatus having the discharge control data adjusting means for adjusting the patronage data.

  According to the present invention, the discharge control data created in the existing image processing (IJ rendering processing) used when printing on the stationary paper by only the main scanning of the IJ head is adjusted for oblique printing, and the obtained data is used. By controlling the operation of the nozzles of the IJ head that is moved obliquely relative to the recording medium, oblique printing can be performed more easily than conventional oblique printing techniques.

1 is a diagram illustrating an outline of a configuration of a multifunction peripheral (MFP) according to an embodiment of an image forming apparatus of the present invention. 1 is a diagram illustrating a configuration of a print control system according to an embodiment of an image forming apparatus of the present invention. It is a figure explaining the operation | movement of diagonal printing in the image forming apparatus of this invention. It is a figure explaining arrangement | positioning of the nozzle in the IJ head used for embodiment of this invention. In the embodiment of the present invention, it is a diagram showing a target image obliquely printed on the paper. FIG. 6 is a diagram illustrating an operation when the image shown in FIG. 5 is obliquely printed on a sheet by the IJ head illustrated in FIG. 4. FIG. 7 is a diagram illustrating the oblique printing operation of FIG. 6 as a relative movement of the IJ head with respect to the paper. It is a figure explaining the existing printing operation | movement which forms the said image (FIG. 5) on the stationary paper. It is a figure explaining the arrangement | sequence of the data for discharge control used for the printing operation (refer FIG. 8) only by the main scan of the existing IJ head. It is a figure explaining the arrangement | sequence of the data for discharge control used for the diagonal printing operation | movement which applied shift adjustment. It is a figure which shows the landing state of the ink droplet in the part which a scanning overlaps in the forward path | route and the backward path | route in diagonal printing of this invention. It is a figure which shows the control flow of the diagonal printing operation | movement of this invention. FIG. 10 is a diagram illustrating an oblique printing operation (second embodiment) by a four-pass printing method for increasing resolution in the image forming apparatus of the present invention. FIG. 10 is a diagram illustrating an oblique printing operation (third embodiment) by a four-pass printing method for increasing resolution in the image forming apparatus of the present invention. It is a figure which shows the example of a display of the operation panel used for selection of operation | movement of diagonal printing mode. It is a figure explaining the diagonal printing operation | movement (Embodiment 5) based on this invention which performs a printing operation only to the partial area | region where the image which exists in only a part of all the printing area | regions belongs. It is a figure explaining the diagonal printing operation (Embodiment 6) based on this invention which performs printing operation only to the partial area | region where the image which exists in only a part of all printing area | region belongs. It is a figure explaining the diagonal printing operation | movement (Embodiment 7) based on this invention which performs printing operation only to the partial area | region where the image which exists in only a part of all printing area | region belongs. It is a figure explaining the operation | movement of the diagonal printing in a prior art. It is a figure which shows the landing state of the ink droplet in the part which a scanning overlaps in the forward path | route and the backward path | route in the conventional diagonal printing. It is a figure which shows the control flow of the printing operation by the conventional diagonal printing system.

Embodiments of the present invention will be described with reference to the accompanying drawings.
The following embodiment shows an example in which the image forming apparatus of the present invention is implemented in an MFP (multi-function peripheral) incorporating a printer that performs an oblique printing operation.
In the MFP according to the present embodiment, when a print request is instructed to a job that uses a function such as a received copy, printer, or facsimile, an image for print output is based on various images input along with this instruction. Data is created and used to control the printing operation of the printer engine.

In this embodiment, as a printing mechanism of the printer engine, paper is conveyed in the sub-scanning direction, an IJ (inkjet) head in which a plurality of nozzles are arranged is moved in the main scanning direction, and the driving of the IJ head is controlled in a dot sequential manner. And a mechanism for recording pixels (ink droplets) arranged on the paper. Note that the plurality of nozzles of the IJ head are arranged at regular intervals in the sub-scanning direction, as will be described in detail later.
The printer engine performs print output by an oblique printing operation. This oblique printing can be carried out by controlling the operation of the printing mechanism without basically changing the mechanism of the printer that performs serial printing by a normal scanning method that does not perform oblique printing. Therefore, it is also possible to implement the operation in the oblique printing mode in addition to the existing printing mode by the normal scanning method.
In the oblique printing operation, the main scanning motor and the sub scanning motor are controlled so that the IJ head linearly moves relative to the recording medium in the printing area, and the ink is synchronized with the movement of the IJ head. Print control is performed to eject droplets.

In the present embodiment, an MFP is taken as an example. However, if the image forming apparatus is equipped with a function for causing a printer engine to perform an oblique printing operation, it is implemented in a single-function image forming apparatus such as a copy, a printer, or a facsimile. Form may be sufficient.
The printer engine of the present embodiment is a system that drives an IJ (inkjet) head using image data for print output, and records pixels (ink droplets) arranged in a dot sequence on a sheet. However, any method other than the inkjet method may be used as long as the pixels arranged in dot-sequential order are recorded on the paper.

[MFP configuration]
A configuration of a multifunction peripheral (MFP) according to the present embodiment will be described with reference to the accompanying drawings.
FIG. 1 is a diagram showing an outline of the configuration of a multifunction peripheral (MFP) according to the present embodiment.
The MFP shown in FIG. 1 includes a main body 900, a paper feed unit 800, a paper discharge unit 700, and a scanner 500.
The main body 900 includes a controller 100, a printer engine unit 200, an operation panel 600, a FAX unit 300, and a PSU (power supply unit) 400.

The controller 100 controls the operation panel 600, the printer engine unit 200, the FAX unit 300, the scanner 500, the PSU (power supply unit) 400, and the like, and controls the operation of each unit of the MFP according to input of job data and the like from the outside. Has a function to control. Note that the functions of the controller 100 include functions such as image processing for processing image data necessary for print output (printing) based on input data.
As a means for realizing such a controller function, the controller 100 includes an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA) 101 that controls the center of the control.

The controller 100 also includes a 0 PUIF 110, an engine IF 112, a FAX IF 116, and an SCNIF 111 for exchanging data with the operation panel 600, the printer engine unit 200, the FAX unit 300, and the scanner 500.
Further, the controller 100 includes a LANIF 113 for exchanging data with a local area network (LAN) and different types of USB (D) IF 114 and USB (H) IF 115 for exchanging data with external devices including storage media. Have.

The printer engine unit 200 includes an IJ head, a driver for the IJ head, a means for moving a carriage on which the IJ head is mounted by a main scanning (head) motor, a means for conveying paper by a sub-scanning (paper conveyance) motor, and the like.
The printer engine unit 200 includes a sensor for detecting the position (movement) of the IJ head, and main scanning and sub-scanning motors used for moving the IJ head and transporting the paper as components of the print control system. Control elements. The print control system will be described in detail later.

An operation panel 600 is an LCD for informing device information such as an operation state of the button 602 and the MFP as a means for inputting an instruction and data to the MFP by a user operation, and displaying information for guiding the user's input operation. (Liquid crystal display device) 601 is included.
The FAX unit 300 has functions necessary for controlling FAX transmission / reception.
The PSU 400 has a function of performing AC-DC conversion and supplying power to each unit that requires DC power.

The scanner 500 has a scanner input function necessary for copying, FAX transmission, scanner distribution, and the like.
The paper feed unit 800 has a mechanism for conveying paper to be supplied to the printer engine unit 200 from the paper feed tray 801 and the paper feed tray 802 to the printer engine unit 200.
The paper discharge unit 700 has a mechanism for conveying the paper discharged from the printer engine unit 200 to each of the paper discharge trays 700 to 702.

[Print control system]
FIG. 2 is a diagram showing a configuration of a print control system according to the embodiment of the image forming apparatus of the present invention.
In the print control system shown in FIG. 2, the control corresponding to the oblique print includes operations peculiar to the present embodiment, but the hardware configuration itself is basically the same as the prior art and is common.
In FIG. 2, the print control system includes a CTL board 1 as a controller that generates a control signal (control data), a control target such as an IJ head 6 that operates under the control of the controller, and control data from the control target. The means for obtaining is a component.

Control targets of the print control system are a head motor 8 that moves a carriage on which the IJ head 6 is mounted and a paper transport motor 10 that transports the paper, in addition to the IJ head 6 that records pixels (ink droplets) on the paper.
In the IJ head 6, a head driver 5 that drives each nozzle in a nozzle row arranged in the sub-scanning direction for ejecting ink droplets is controlled by a HEADCTL (head controller) 2 b of the CTL board 1.
In the head motor 8 that moves the carriage on which the IJ head 6 is mounted, the motor driver 7 is controlled by the CTL board 1.
In the paper transport motor 10 that transports the paper, the motor driver 9 is controlled by the CTL board 1.
The means for acquiring control data corresponds to the means for detecting the position of the IJ head 6. The analog position signal detected by the encoder 12 is converted into digital data through the A / D converter 11 and sent to the CTL board 1.

The CTL board 1 has a CPU (Central Processing Unit) 2a and a HEADCTL 2b on a SoC (System On Chip) module 2. In addition, a ROM (Read Only Memory) 3 and a DRAM (Dynamic Random Access Memory) 4 are provided under the control of the SoC module 2.
The ROM 3 is a memory for storing programs, data, and the like used by the CPU 2a or HEADCTL 2b in order to realize the operation of the print control system and the processing of image data used for print output. The DRAM 4 is a memory used as a memory for temporarily storing data generated by the program or a work memory for storing data necessary for the operation of the software program. That is, the SoC module 2, the ROM 3, and the DRAM 4 constitute a computer.

As described above, the computer on the CTL board 1 controls the IJ head 6, the head motor 8 and the paper transport motor 10 in an integrated manner to constitute a print control system for performing a print operation.
This print control system controls the head motor 8 and the paper transport motor 10 so that the IJ head 6 moves obliquely with respect to the paper at a constant speed in the print area when performing oblique printing, and the HEADCTL 2b is connected to the IJ head 6. Ink droplets are ejected in synchronization with the movement, and the desired printing control is performed.
In the MFP of this embodiment (FIG. 1), an example in which the print control system of FIG. However, the means for realizing the above functions of the CTL board 1 in the print control system of FIG. 2 may be an element on the controller 100 side that functions as the main control unit.

[Slant printing]
The oblique printing performed by the printing control system will be described in detail.
The printer engine unit 200 of the MFP includes an IJ head 6, a sheet conveying unit as a recording medium, a carriage moving unit on which the IJ head 6 is placed, and a print control system (FIG. 2).
The IJ head 6 has a nozzle row in which nozzles for ejecting ink droplets are arranged at regular intervals in the sub-scanning direction (see the embodiment in FIG. 4 described later), and the head driver 5 drives the nozzles. The sheet conveying means conveys the sheet in the sub-scanning direction by driving the sheet conveying motor 10. The carriage moving means moves the IJ head 6 mounted on the carriage in the main scanning direction by driving the head motor 8.
The print control system (FIG. 2) centrally controls each drive of the paper transport motor 10, the head motor 8, and the head driver 5 in order to perform an oblique print operation. In other words, the driving of the paper transport motor 10 and the head motor 8 is controlled so that the IJ head 6 moves relative to the paper obliquely at a predetermined constant speed and with a predetermined inclination. In addition, print control is performed to eject ink droplets at regular intervals by driving the nozzles in synchronization with the movement of the IJ head 6 described above, based on the ejection control data obtained by the IJ rendering process based on the original image.

  The speed condition for moving the IJ head 6 obliquely and the nozzle drive timing can be basically determined arbitrarily. However, in this embodiment, the following conditions must be satisfied. That is, one of the conditions is to use data obtained by an IJ rendering process performed when an image is formed on a stationary sheet by a normal scanning method. Another condition is that the pixel group formed by oblique printing forms a pixel group in which the pixels are arranged in the main and sub scanning directions in the same manner as the reproduction image of the normal scanning method. . That is, in order to obtain this pixel configuration, the speed and inclination when the IJ head 6 is relatively moved obliquely and the nozzle drive timing are determined as the oblique printing operation conditions.

In order to satisfy the above-described oblique printing operation condition, the printing control system of this embodiment includes a head movement control unit, a recording medium (paper) conveyance control unit, an oblique printing operation control unit, an image processing unit, and an ejection control data adjustment unit. As a function. Here, each of the above-described means performs operations such as the following control and processing.
The head movement control means controls the driving of the head motor 8 as the movement means so as to move the IJ head 6 at a predetermined constant speed during the printing period.
The recording medium conveyance control unit controls the driving of the sheet conveyance motor 10 as a conveyance unit so that the sheet can be conveyed at a predetermined constant speed and oblique printing can be performed in the printing period.

  Further, the oblique printing operation control means corresponds to the relationship of the sheet conveying speed to the moving speed of the IJ head 6 determined to print the pixel groups arranged in the main and sub scanning directions (corresponding to “diagonal coefficient” described later). ), The head movement control means and the recording medium conveyance control means are operated. Further, in accordance with the movement of the IJ head 6 that moves obliquely relative to the paper, the ejection control data for oblique printing used for each pixel constituting the pixel group (refer to the description of the ejection control data adjusting means described later). Thus, each nozzle of the inkjet head is operated.

Further, the image processing means controls the movement of the IJ head 6 by the head movement control means, and creates ejection control data used for printing the reproduced image of the original image on the stationary paper from the original image data. The ejection control data indicates pixel group data arranged in the main and sub scanning directions obtained by IJ rendering processing performed when an image is formed on a stationary sheet by a normal scanning method.
The discharge control data adjusting means adjusts the discharge control data created by the image processing means as the oblique print operation control data used in the oblique print operation control means. The adjustment of the ejection control data is performed by increasing the shift amount of the pixel row data arranged in the sub-scanning direction one pixel at a time in the print timing order in the pixel group data obtained by the IJ rendering process of the image processing unit. Perform the shift operation. By this operation, the arrangement of data is changed, and adjustment to discharge control data for oblique printing is performed.

The print control system of the present embodiment having the above-described function performs an oblique print operation as follows.
The print control system performs compression, expansion, scaling, etc. necessary for making image data suitable for IJ rendering by the image processing means for the output target image data (original image data) received together with the print request. After data processing, IJ rendering processing is performed. This IJ rendering process is a process for obtaining data of pixel groups arranged in the main and sub scanning directions as ejection control data used when an image is formed on a stationary sheet by a normal scanning method.
Further, the ejection control data adjustment means performs a data adjustment operation for shifting the pixel row data arranged in the sub-scanning direction in the pixel group obtained by the IJ rendering process in the sub-scanning direction by increasing the shift amount by one pixel in order of the print timing. Is performed for each pixel column data. By performing this adjustment operation, the arrangement of data is changed.

Further, the print control system is configured so that the oblique print operation control means follows the relationship of the sheet conveyance speed with respect to the moving speed of the IJ head 6 determined to print the pixel groups arranged in the main and sub scanning directions. The movement control unit and the recording medium conveyance control unit are operated. Further, the ejection control data for oblique printing adjusted by the ejection control data adjusting means is used for driving each nozzle of the IJ head 6 at a driving timing in accordance with the movement of the IJ head 6 that moves relative to the sheet obliquely. Thus, a pixel group is formed by oblique printing.
The image formed on the paper by such a printing operation is a normal reproduction image of the original image even if the IJ head 6 moves obliquely relative to the paper. This oblique printing operation will be described in more detail with reference to an embodiment exemplified below.

“Embodiment 1”
The basic operation of oblique printing performed by the control of the printing control system (FIG. 2) is performed by reciprocating the IJ head 6 having nozzle rows arranged at regular intervals in the sub-scanning direction on the paper in the main scanning direction. An embodiment in which an operation of forming an image by driving a nozzle will be described as an example.
In this embodiment, during the printing operation for one sheet, the print control system always conveys the sheet at a constant speed.
Further, the printing control system employs a mechanism that repeats reciprocating movement by reversal switching in the main scanning direction as a moving means of the IJ head 6, and provides a predetermined printing period for each reciprocating movement, and the IJ head 6 is moved during that period. It is made to move at a predetermined constant speed.

FIG. 3 is a diagram for explaining an oblique printing operation in the present embodiment.
The IJ head 6 having nozzles for ejecting ink droplets prints on the paper with the ink droplets ejected from the nozzles to form pixels while reciprocating in the main scanning direction orthogonal to the sub-scanning direction for transporting the paper.
In the oblique printing method, since the sheet is always conveyed during the printing operation for one sheet, the printing area of the IJ head 6 passing over the sheet is inclined as shown in FIG. In addition, the print area is inclined on the forward path (movement of the IJ head 6 from position A to position B in FIG. 3A) and the return path (movement of the IJ head 6 from position B to position C in FIG. 3). Vice versa.

However, in the pixel group formed by the oblique printing, as described above as the operation condition of the oblique printing, the arrangement of the pixels is arranged in the main and sub scanning directions (described later with reference to FIGS. 7 and 8). Explained in the example). That is, the same image as the reproduced image when the image is formed by scanning only the IJ head on the stationary paper, which is a normal scanning method performed so far, is formed.
In FIG. 3B, the fact that the printed pixels are arranged in the main scanning direction is indicated by the pixel column line of the pixels formed when the IJ head 6 moves from position A → position B → position C in FIG. Represents.
When performing oblique printing according to this embodiment using the IJ head 6 having nozzle rows arranged at regular intervals in the sub-scanning direction, pixels arranged in the main scanning direction after printing are arranged back and forth in the sub-scanning direction of the nozzle row. Printed by each nozzle. This is because the pixels arranged in the main scanning direction are printed by the nozzles arranged back and forth in the sub-scanning direction in accordance with the operating conditions described above as the operating conditions of this oblique printing, and the normal scanning method for printing on stationary paper This is different from the operation of printing pixels arranged in the main scanning direction with the same nozzle.

The IJ head 6 is a multi-pass printing method in which the head passes the same image area on the paper surface a plurality of times by scanning the forward path and the backward path, and as shown in FIG.
In the multi-pass printing method, it is required to always make the overlapping area in a plurality of passes uniform.
The example of FIG. 3 is a two-pass printing method. In the two-pass printing, in order to always make the overlapping area uniform, each scanning path (position A → position B, position B → position C, position C → position D...) Of the IJ head 6 in the sub-scanning direction. The moving distance depends on a specification that advances a distance that is half (1/2) the length of the nozzle row of the IJ head 6 in the sub-scanning direction.

FIG. 4 is a diagram illustrating the arrangement of nozzles in the IJ head used in this embodiment.
In the present embodiment, as shown in FIG. 4, two rows and nine rows of nozzles are provided, in which two rows (a, b) of nozzle rows in which nine nozzles (1 to 9) are arranged at regular intervals in the sub-scanning direction are provided. A holding IJ head 6n is used.
Each nozzle row shown in FIG. 4 shows an example having nine rows of nozzles for convenience of explanation. Originally, nozzle rows having values such as 192 rows and 384 rows are used. In this embodiment, the interval between the nozzles arranged in the sub-scanning direction is, for example, a value that can print the most common dpi in the sub-scanning direction, and the interval between two nozzles arranged in the main scanning direction is the same. The value shall be taken. Further, although the IJ head 6n has two nozzle rows, it may be a single or three or more rows.
Among the nozzles in the IJ head 6n shown in FIG. 4, a white circle “◯” represents a state where ink is not ejected, and a black circle “●” represents a state where ink is ejected. . The example of FIG. 4 represents a state where “only nozzles in 4 rows and b columns are ejected”.

Next, an oblique printing operation performed using the IJ head 6n shown in FIG. 4 will be described using a specific example.
First, a target image for oblique printing taken as an example is shown.
FIG. 5 is a diagram illustrating a target image that is obliquely printed on a sheet in the present embodiment. In the drawing, a straight line Ls drawn in the horizontal direction in the image area on the paper is shown, and here, the straight line Ls is set as an image to be obliquely printed.
Note that the direction of the straight line Ls is a direction orthogonal to the paper conveyance (sub-scanning) direction indicated by the arrow in the drawing, and coincides with the movement (main scanning) direction of the IJ head 6n.

FIG. 6 is a diagram for explaining the operation when the target image shown in FIG. 5 is obliquely printed on a sheet by the IJ head 6n illustrated in FIG.
FIG. 6 shows that the paper is displaced from position A → position A ′ → position A ″ by the conveyance in the sub-scanning direction indicated by the arrow in the figure, and at the same time, the IJ head 6n is indicated by the arrow in the figure. By the movement in the main scanning direction shown, the IJ head 6n is displaced from position A → position A ′ → position A ″. In other words, as an oblique printing operation, when the paper is at position A, the IJ head 6n is simultaneously at position A, and the same positional relationship is also displaced at positions A ′ and A ″.

The line width of the straight line Ls of the image to be obliquely printed corresponds to four nozzles of the nozzle row arranged in the sub-scanning direction in the IJ head 6n shown in FIG. 4, and the straight line Ls is obtained by causing these nozzles to perform a discharge operation. Is printed.
Therefore, in FIG. 6, at the first print timing when the paper and the IJ head 6n are respectively at the position A, the print control system discharges ink from the nozzles (see FIG. 4) of 1 to 4 rows of the IJ head 6n. The nozzle is driven using the control data.
The second printing timing is when the paper and the IJ head 6n are displaced to the position A ′. That is, the second printing timing is when the IJ head 6n has displaced from the first printing timing corresponding to twice the interval in the main scanning direction of the two nozzle rows provided on the head. At this print timing, ink is ejected from the nozzles of 2 to 5 rows of the IJ head 6n. The difference in the nozzle ejection operation performed at the second printing timing from the beginning is that the nozzle shifted by one in the sub-scanning direction is caused to perform the ejection operation and the straight line Ls drawn in the main scanning direction is printed. .
The time when the paper and the IJ head 6n are displaced at the position A ″ is the third printing timing. At this printing timing, the IJ head 6n is caused to perform an operation of ejecting ink from the nozzles of 3 to 6 rows shifted by one in the sub-scanning direction further than at the second printing timing.

FIG. 7 is a diagram illustrating the oblique printing operation of FIG. 6 as a relative movement of the IJ head 6n with respect to the sheet.
If the operation of FIG. 6 in which the paper and the IJ head 6n are displaced by the oblique printing operation is regarded as the relative movement of the IJ head 6n with respect to the paper, the IJ head 6n with respect to the stationary paper is shown in FIG. As shown by the arrow in the middle, it is displaced obliquely.
The print timing is when the IJ head 6n is displaced obliquely from position A → position A ′ → position A ″ to the position A, position A ′, position A ″. At this timing, the nozzle is operated by the discharge control data for printing the straight line Ls. The ink ejection operation of the nozzles at the positions A, A ′, and A ″ is the same as in FIG.
Accordingly, the pixels (“●”) of the straight line Ls printed at the positions A, A ′, and A ″ in FIG. 7 are reproduced as straight lines drawn in the main scanning (horizontal) direction on the paper. I understand that

As described above, the ejection control with the shift adjustment necessary for the oblique printing is performed at the printing timing when the paper and the IJ head 6n are displaced to reach the positions A, A ′, and A ″. Each nozzle of the IJ head 6n is operated using the data for operation.
Here, the adjustment of the discharge control data will be described by taking an example of oblique printing in which the straight line Ls in the present embodiment is a printing target.
In the oblique printing, as described above, unlike the scanning method using only the main scanning of the IJ head that is normally performed when printing on a stationary sheet, sub-scanning by sheet conveyance is performed simultaneously with the main scanning. For this reason, it is necessary to use the discharge control data adapted to the operation of the main and sub simultaneous scanning methods as the discharge control data of each nozzle of the IJ head 6n.
Since this discharge control data required for the oblique printing operation can be obtained without using a high-level image processing and taking a new development burden, in the present invention, an image is formed by the above-described normal scanning method performed on a stationary sheet. Data obtained by the IJ rendering process performed at the time of use is used.

Therefore, an existing printing operation performed on a stationary sheet using the normal scanning method based only on the main scanning of the IJ head will be described by taking the straight line Ls as a printing target as an example.
FIG. 8 is a diagram for explaining an existing printing operation for forming the image (FIG. 5) on a stationary sheet.
In the printing operation when the normal scanning method using only the main scanning is employed, the IJ head 6n is displaced in the main scanning direction as indicated by the arrow in FIG.
The print timing is when the IJ head 6n is displaced from the position A → position A ′ → position A ″ in the main scanning direction to the position A, position A ′, position A ″. Yes, at this timing, the nozzle is operated by the ejection control data for printing the straight line Ls.
The ejection control data used at this time is data in which the orientation of the original image is maintained when the original image is represented by data drawn by a group of pixels arranged in the main and sub scanning directions in an image area of a predetermined size. It is. That is, data obtained by rendering the original image can be used for ejection control as it is.

FIG. 9 is a diagram for explaining the arrangement of ejection control data used for a printing operation (see FIG. 8) by only main scanning of an existing IJ head. This figure is data indicating nozzles to be driven to eject ink in nozzle rows arranged in the sub-scanning direction in the order of print timing. That is, at each of the printing timings of position A, position A ′, and position A ″, the nozzles that eject ink in the nozzle array are nozzles 1 to 4 of IJ head 6n as shown in FIG. Reference).
Accordingly, the arrangement of the print data used as the ejection control data in FIG. 9 is data for designating the nozzles of 1 to 4 rows in each of the nozzle rows of a and b2.
In FIG. 9, data is expressed in a format in which the nozzle to be driven is instructed, but actually, discharge control data that instructs whether or not to discharge each nozzle in the nozzle row is used for the control operation. Further, the discharge control data is managed so as to be used in the order of the print timings of position A, position A ′, and position A ″.
As described above, all the pixels of the straight line Ls (see “●” in FIG. 8) printed at the positions A, A ′, and A ″ according to the ejection control data in FIG. 9 are the IJ head 6n. 1 to 4 nozzles (see FIG. 4).
By using this ejection control data and performing a printing operation using a scanning method based only on the main scanning, a linear image drawn in the main scanning (horizontal) direction on the paper is reproduced.

The ejection control data used when performing a printing operation using a normal scanning method based only on main scanning on a stationary sheet is the data obtained by rendering the original image (FIG. 9), and the normal line Ls is normal. An image (FIG. 8) is reproduced.
In order to use the data (FIG. 9) obtained after the rendering process for oblique printing, adjustment to the discharge control data corresponding to the conveyance of the paper in the sub-scanning direction added as an operation condition in oblique printing must be performed. I must.
This adjustment is basically an operation of shifting the pixel row data arranged in the sub-scanning direction in the pixel group obtained by the IJ rendering process in the sub-scanning direction by increasing the shift amount one pixel at a time in the print timing order. This data shift adjustment operation is performed on each pixel column data arranged in the sub-scanning direction.

When the straight line Ls is to be printed, adjustments to the pixel array data (corresponding to the nozzle ejection control in FIG. 8) at position A, position A ′, and position A ″ shown in FIG. 9 obtained by rendering the original image are performed. do. In this adjustment, the pixel array data is shifted in the sub-scanning direction by increasing the shift amount by one pixel at a time in the printing timing order of position A → position A ′ → position A ″.
The pixel column data used at the timing for printing the pixel column data at the position A ′ next to the pixel column data at the first position A is adjusted to shift the pixel column data obtained by the rendering process by one pixel in the sub-scanning direction. .
Further, the pixel column data used at the timing of printing the pixel column data at the position A ″ next to the pixel column data at the position A ′ is adjusted by shifting the pixel column data obtained by the rendering process by two pixels in the sub-scanning direction. I do.

FIG. 10 is a diagram for explaining the arrangement of the ejection control data used in the oblique printing operation with the shift adjustment applied. This figure is data indicating nozzles to be driven to eject ink in nozzle rows arranged in the sub-scanning direction in the order of print timing.
That is, at the printing timing at position A, the nozzles that eject ink in the nozzle row are the nozzles in the first to fourth rows of the IJ head 6n.
Further, at the printing timing of the position A ′, the nozzles that eject ink in the nozzle row are the nozzles of 2 to 5 rows of the IJ head 6n.
Further, at the printing timing of the position A ″, the nozzles for ejecting ink in the nozzle row are the nozzles of 3 to 6 rows of the IJ head 6n.
Note that the discharge control data used in the oblique printing operation with the shift adjustment of this example corresponds to the nozzle discharge control operation of FIG.

Incidentally, during oblique printing, the speed in the main scanning direction of the carriage on which the IJ head 6n is placed and the speed in the sub-scanning direction of the conveyed paper are both constant. Here, in each nozzle, the main scanning speed between pixels to be printed is Vm, and the sub-scanning speed is Vs.
The nozzle discharge sampling time for determining the print timing (in the example of FIG. 7, the time difference between the positions A and A ′) and the movement distance in the sub-scanning direction (in FIG. 7 the nozzle interval in the sub-scanning direction) are as described above. It is uniquely determined by the oblique printing operation conditions.
In the example of FIG. 7, if the distance between pixels to be printed is the same in both the main and sub scanning directions, Vm = Vs.
Here, the sheet conveyance speed (sub-scanning speed Vs) with respect to the moving speed (main scanning speed Vm) of the IJ head 6n determined to print the pixel groups arranged in the main and sub-scanning directions by oblique printing. The relationship is expressed by, for example, a speed ratio (Vs / Vm). The speed ratio (Vs / Vm) represents the degree of inclination when the IJ head 6n moves obliquely relative to the paper. In this embodiment, the speed ratio (Vs / Vm) is referred to as “oblique coefficient” and is used as a processing parameter. When Vm = Vs, the oblique coefficient is 1.

As described above, the printing operation is performed by determining the main scanning speed Vm, the sub-scanning speed Vs, and the printing timing according to the oblique printing operation conditions.
However, in practice, due to the unique characteristics of the device, even if the operation is performed according to the same theoretical value, the pixel row line due to oblique printing does not follow the theoretical value in each of the forward and backward scans, and the ink droplet due to the tilt error that occurs The landing position deviation (see FIG. 20) reduces the image quality.
Therefore, in this embodiment, by adjusting the relationship between the main scanning speed Vm and the sub-scanning speed Vs, an error in inclination when the IJ head 6n moves obliquely relative to the paper is corrected.
FIG. 11 is a diagram illustrating a landing state of ink droplets in a portion where scanning is overlapped in the forward pass and the return pass in the oblique printing of the present embodiment.
FIG. 11 shows the landing position deviation (see FIG. 20) of the ink droplet caused by the difference in the characteristics of the transport mechanism and the movement in the forward path and the backward path by adjusting the relationship between the main scanning speed Vm and the sub scanning speed Vs in this embodiment. As shown, it can be corrected.

In order to perform the above correction, an experiment is performed in which a theoretical value is set in the target device and an oblique printing operation is performed, and an operation condition that can correct an error inherent to the device is found. Based on the experience result obtained in this way, an adjustment amount for performing an appropriate oblique printing operation is obtained in advance.
As the adjustment means in the equipment, for example, in the equipment of the corresponding model, by providing means for adjusting the control target values of the main scanning speed Vm and the sub-scanning speed Vs that are generally set as default values based on the above experience values. Can be implemented. When the relationship between the main scanning speed Vm and the sub-scanning speed Vs is adjusted, the printing timing (slur discharge sampling time) must be changed.

Next, the control flow of the above-described oblique printing operation of the present embodiment performed by the printing control system (FIG. 2) is shown below.
FIG. 12 is a diagram showing a control flow of the oblique printing operation of the present embodiment.
According to the control flow of FIG. 12, when a status change corresponding to a print request occurs in the printer, the SoC 2 computer starts this control flow.
After startup, first, image data to be printed is input from an external device such as a PC, smart device, USB memory or SD card (step S101).
The input image data is subjected to data processing (compression / decompression / rotation / magnification, etc.) necessary for making it adaptable to subsequent IJ rendering, and then temporarily stored in a memory such as DRAM 4 ( Development) (step S102).

After that, as the IJ rendering, the arrangement of the image data is arranged in the order in which the ink droplets are actually ejected from the nozzles of the IJ head 6n in consideration of the arrangement of the nozzle rows of the IJ head 6n and the reciprocating operation direction. The nozzle main control data is obtained (step S103).
The processing result is stored again in the memory (step S104).
Next, as a processing procedure for adapting to the operation according to the oblique printing condition, first, an oblique coefficient is calculated (step S105). The oblique coefficient indicates an operation condition of oblique printing, and the relationship between the sheet conveyance speed and the moving speed of the IJ head 6n is expressed as a speed ratio, for example. Therefore, calculation of the speed ratio and the like is performed here. When the landing position deviation described with reference to FIG. 11 is corrected, the correction condition is reflected in the oblique coefficient. Therefore, the calculation of the oblique coefficient is an operation including the correction condition.

The image data used for the oblique printing stored in the memory in step S104 is transferred to HEADCTL 2b that controls the head driver 5 that drives the IJ head 6 in accordance with the main scanning encoder signal output from the encoder 12 (step S106).
At this time, the image data after rendering processing to be transferred is ejection control data used when performing a printing operation using a normal scanning method based only on main scanning on a stationary sheet. In addition, an oblique coefficient indicating the oblique printing operation condition calculated in step S105 is added to the image data. The encoder signal is a signal synchronized with the print timing.

Next, the HEADCTL 2b that receives the transferred image data and the oblique coefficient adjusts the received image data to ejection control data used for oblique printing.
This adjustment corresponds to the shift adjustment of the pixel column data described above with reference to FIG. That is, in the pixel groups arranged in the main and sub scanning directions before the rendering process after the rendering process, the pixel row data used for the ejection control of all the nozzles of the nozzle row of the IJ head 6n are sequentially shifted by one pixel in order of the print timing. Increase and shift in the sub-scanning direction.
Further, based on the adjusted ejection control data, a control signal for driving all nozzles of the IJ head 6 n in accordance with the main scanning encoder signal is generated and output to the head driver 5. In addition, when the operation condition of the oblique printing instructed by the oblique coefficient becomes a setting different from the condition set by default due to, for example, the above-described landing position deviation correction, the head driver is printed at the print timing according to the changed condition. 5 is controlled.

The head driver 5 that receives the drive control signal output by the HEADCTL 2b drives the IJ head 6n according to the input control signal, that is, the mask signal that indicates whether or not to eject the nozzle, and ejects ink droplets from the nozzle. Printing is performed (step S107). Here, when the operation of HEADCTL 2b that outputs a control signal to the head driver 5 is performed in units of pixel column data used for ejection control of all the nozzle columns of the IJ head 6n over an oblique printing region, step S106 → This is a procedure for repeating the operation of S107. Further, in this case, every time the HEADCTL 2b outputs, the above-described data shift adjustment operation is performed to increase the shift amount of the pixel row data in the order of print timing by one pixel and shift in the sub-scanning direction.
After confirming that the printing operation in step S107 has been completed over the entire area where the oblique printing is performed, the operation of this control flow is terminated.

In the control flow of FIG. 12, adjustment is performed by a data shift operation with respect to ejection control data obtained by rendering processing employed when printing on a stationary sheet by a normal scanning method performed only by main scanning of the IJ head.
In this way, it is possible to easily perform oblique printing that uses the data of rendering processing of the existing scanning method and outputs an image that is not inferior to the existing scanning method by a simple data operation called data shift. The advantage of reducing noise and vibration is also obtained.
Further, correction of the landing position deviation (FIG. 20) peculiar to the oblique printing can be performed in the control process of the oblique printing operation.

“Embodiment 2”
In the first embodiment, as a basic operation of oblique printing controlled by the printing control system (FIG. 2), the IJ head 6 having nozzle rows arranged at regular intervals in the sub-scanning direction on the conveyed paper is moved in the main scanning direction. The operation of printing by driving the nozzle back and forth during each reciprocating printing period was shown. In the above operation, the IJ head 6 reciprocates on the paper, and the head performs a printing operation on the same image area on the paper surface a plurality of times (twice in the example of FIG. 3) by the forward and backward scanning. The multi-pass printing method is used. However, the pixels to be printed in each of the forward pass and the return pass are overlapped (see FIG. 11), so the resolution does not increase.

In the present embodiment, an embodiment in which an operation condition for increasing the resolution of an image to be printed is added to the oblique printing operation shown in the first embodiment.
In order to increase the resolution, the print area corresponding to the initially determined resolution (for example, the resolution of the original image) is subdivided and arranged in the main and sub scanning directions in the print period provided for each subdivision area. A method of printing a pixel group is adopted.
In order to perform oblique printing in accordance with the above method, the print control system causes the head movement control means and the recording medium conveyance control means to perform an operation to subdivide the print area, and the IJ head 6n for each subdivision area. It is necessary to cause the nozzle to perform a printing operation in synchronization with the movement of the nozzle.

The following first to third modes are conceivable as modes for carrying out oblique printing based on the basic method described above.
The first is a form in which subdivision is performed in the sub-scanning direction and printing is performed on each subdivided print area, and this form can increase the resolution in the sub-scanning direction.
The second is a form in which subdivision is performed in the main scanning direction and printing is performed on each subdivided print area. With this form, the resolution in the main scanning direction can be increased.
The third is a form in which sub-scanning and main scanning are subdivided and printing is performed on each subdivided print area. With this form, the resolution in both the sub-scanning and main scanning directions can be increased.
In the present embodiment, an embodiment that adopts the first embodiment will be described.
An embodiment that adopts the second embodiment will be described later in “Embodiment 3”. In addition, the embodiment adopting the third embodiment can be implemented by combining the second embodiment and the third embodiment, and thus the description is omitted.

FIG. 13 is a diagram for explaining an oblique printing operation by a four-pass printing method for increasing the resolution in the present embodiment.
In the oblique printing method, since the sheet is always conveyed during the printing operation for one sheet, the printing area of the IJ head 6n passing over the sheet is inclined as shown in FIG. Further, the inclination of this printing area is reversed on the forward path (movement from position A → position B, position C → position D) and on the return path (movement from position B → position C, position D → position E).
However, in the pixel group formed by oblique printing, as described above, the arrangement of the pixels is arranged in the main and sub scanning directions (see the description of FIGS. 7 and 8). That is, the same image as the reproduced image when the image is formed by scanning only the IJ head on the stationary paper, which is a normal scanning method performed so far, is formed.

Therefore, in FIG. 13B, the printed pixels are arranged in the main scanning direction when the IJ head 6n moves from position A → position B → position C → position D → position E in FIG. This is represented by a pixel column line of the pixel to be processed. FIG. 13B is an exploded view illustrating the pixel columns formed in each of the forward path and the backward path, with the line type being changed.
Further, the IJ head 6n is a multi-pass printing method in which the head passes the same image area on the paper surface a plurality of times by scanning in the forward path and the backward path, and as shown in FIG. That is, in FIG. 13C, the exploded view of FIG. 13B is superimposed so as to represent the actual printing state.
The example of FIG. 13 is a 4-pass printing method. In 4-pass printing, the movement distance in the sub-scanning direction of each scanning path (position A → position B, position B → position C, position C → position D → position E...) Of the IJ head 6n is the IJ head 6n. Depends on the specification to advance a distance of 1/4 of the length of the nozzle row in the sub-scan direction.

In the present embodiment, as shown in FIG. 13C, the print area is subdivided in the sub-scanning direction so that pixels to be printed do not overlap each other in the forward pass and the return pass of the oblique printing by the 4-pass printing method.
Therefore, for example, when the moving speed of the IJ head 6n moving in the main scanning direction is not changed, the print area is set to 4 in the sub scanning direction by changing the setting to reduce the conveying speed of the paper conveyed in the sub scanning direction to ¼. The resolution can be subdivided into four and the resolution can be increased four times. In this case, it is not necessary to change the printing timing. However, when the speed of the moving speed of the IJ head 6n is also changed, the print timing is synchronized and must be changed.
In addition, along with the change in the operating conditions for increasing the resolution, it is necessary to adapt the ejection control data used for driving the nozzles of the IJ head 6n. The technique required for this adaptation can be implemented by applying an existing image processing technique used for higher resolution. Further, when the original image has a high resolution and is used with a reduced resolution in normal operation, the data of the original image is used retroactively.

As described above, in this embodiment, oblique printing with an increased resolution in the sub-scanning direction can be performed by performing a multi-pass operation so as to subdivide the print area in the sub-scanning direction.
Also, with diagonal printing so far, when increasing the resolution, as described in [Background Technology] above, it is necessary to separately perform diagonal printing rendering processing for high resolution, increasing the development man-hours and storing necessary programs The area was increased. Such a disadvantage is not incurred in the present embodiment, and can be realized by using a rendering process employed in a normal serial inkjet printer.

“Embodiment 3”
As in the second embodiment, the present embodiment shows an embodiment in which an operation condition for increasing the resolution of an image to be printed is added to the oblique printing operation shown in the first embodiment.
In the present embodiment, the print area is subdivided in the main scanning direction, and printing is performed on each subdivided print area, and this form increases the resolution in the main scanning direction.

FIG. 14 is a diagram for explaining an oblique printing operation by a 4-pass printing method for increasing the resolution in the present embodiment.
In the oblique printing method, since the sheet is always conveyed during the printing operation for one sheet, the printing area of the IJ head 6 passing on the sheet is inclined as shown in FIG. Further, the inclination of this printing area is reversed on the forward path (movement from position A → position B, position C → position D) and on the return path (movement from position B → position C, position D → position E).
However, in the pixel group formed by oblique printing, as described above, the arrangement of the pixels is arranged in the main and sub scanning directions (see the description of FIGS. 7 and 8). That is, the same image as the reproduced image when the image is formed by scanning only the IJ head on the stationary paper, which is a normal scanning method performed so far, is formed.

Therefore, in FIG. 14B, the printed pixels are arranged in the main scanning direction when the IJ head 6 moves from position A → position B → position C → position D → position E in FIG. This is represented by a pixel column line of the pixel to be processed. FIG. 14B is an exploded view illustrating the pixel columns formed in each of the forward path and the backward path, with different line types.
Further, the IJ head 6n is a multi-pass printing method in which the head passes the same image area on the paper surface a plurality of times by scanning in the forward path and the backward path, and as shown in FIG. That is, in FIG. 14C, the exploded view of FIG. 14B is superimposed so as to represent the actual printing state.
The example of FIG. 14 is a 4-pass printing method. In 4-pass printing, the movement distance in the sub-scanning direction of each scanning path (position A → position B, position B → position C, position C → position D → position E...) Of the IJ head 6n is the IJ head 6n. Depends on the specification to advance a distance of 1/4 of the length of the nozzle row in the sub-scan direction.

In the present embodiment, as shown in FIG. 14C, the print area is subdivided in the main scanning direction so that pixels to be printed are not overlapped in the forward pass and the return pass of oblique printing by the 4-pass printing method.
Therefore, for example, when the conveyance speed of the paper moving in the sub-scanning direction is not changed, the print area is set to 4 in the main scanning direction by changing the setting to reduce the moving speed of the IJ head 6n moving in the main scanning direction to ¼. The resolution can be subdivided into four and the resolution can be increased four times. In this case, it is not necessary to change the printing timing. However, when the paper transport speed is also changed, the printing timing is synchronized, so it must be changed.
In addition, along with the change in the operating conditions for increasing the resolution, it is necessary to adapt the ejection control data used for driving the nozzles of the IJ head 6n. The technique required for this adaptation can be implemented by applying an existing image processing technique used for higher resolution. Further, when the original image has a high resolution and is used with a reduced resolution in normal operation, the data of the original image is used retroactively.

As described above, in this embodiment, oblique printing with an increased resolution in the main scanning direction can be performed by performing a multi-pass operation so as to subdivide the print area in the main scanning direction.
Also, with diagonal printing so far, when increasing the resolution, as described in [Background Technology] above, it is necessary to separately perform diagonal printing rendering processing for high resolution, increasing the development man-hours and storing necessary programs The area was increased. Such a disadvantage is not incurred in the present embodiment, and can be realized by using a rendering process employed in a normal serial inkjet printer.

“Embodiment 4”
In the first embodiment, the embodiment related to the basic oblique printing operation controlled by the printing control system (FIG. 2) has been described. In the second and third embodiments, the operation conditions for increasing the resolution of an image to be printed in the oblique printing operation of the first embodiment are shown.
However, the basic oblique printing operation and the oblique printing operation in accordance with the operation condition added to increase the image resolution may cause a mismatch depending on the intention of the user who uses the device, the purpose of use of the printing result, and the like.
For example, a user who thinks that it is desirable to print quickly even if the image quality of the printed image is somewhat bad may have the intention of not performing the oblique printing operation. This is because the oblique printing operation has a higher possibility of scanning one reciprocation more than the normal printing operation (the operation of printing on the stationary paper by the normal scanning method performed only by the main scanning of the IJ head 6n). This is one of the factors that decrease the printing speed. Of course, the diagonal printing operation is a necessary function for users who place importance on the merit of the diagonal printing operation.

Therefore, the device is equipped with a function to perform normal print mode and oblique print mode as the print mode, and the print control system operates in the print mode selected from multiple types of print modes including differences in resolution. I do.
The selection of the print mode is in accordance with an instruction of an operation signal input by an operation of the user's key or the like on the LCD 601 of the operation panel 600 which is an operation means for performing an operation instructed from the outside by the user.
FIG. 15 is a diagram illustrating a display example of the operation panel 600 used for selecting an operation in the oblique printing mode.
On the LCD 601 of the operation panel 600, as shown in FIG. 15, an input screen 601d for accepting a print mode setting operation is displayed.

As printing mode options, the normal printing mode and the diagonal printing mode are further divided into two categories.
Since the oblique printing mode has less noise and vibration than the normal printing mode described below, it is distinguished from the normal printing mode by adding the keyword “SHIZUKA” and adding the keyword “SHIZUKA”. Also, the oblique printing mode is divided into low resolution and high resolution. Since the low resolution corresponds to the operating condition for increasing the printing speed, the keyword “fast” is attached. On the other hand, the high resolution corresponds to the operating condition that sharpens the printed image, so the keyword “clean” is attached.
The normal printing mode is an operation mode in which printing is performed on a stationary sheet by a normal scanning method performed only by main scanning of the IJ head 6n. Normal printing modes are also divided into low resolution and high resolution. Since the low resolution corresponds to the operating condition for increasing the printing speed, the keyword “fast” is attached. On the other hand, the high resolution corresponds to the operating condition that sharpens the printed image, so the keyword “clean” is attached.

As described above, the input screen 601d further divides the normal printing mode and the diagonal printing mode into two modes, and displays four categories of options. For example, check boxes as shown in FIG. Provide. The user performs an operation to select a desired print mode for the check box.
By making it possible to select the print mode based on the user's operation input, the device performance can be improved without causing a mismatch with the user's intention.

“Embodiment 5”
In each of the above embodiments, regardless of the image to be printed, the IJ head 6n is reciprocated in the main scanning direction over the entire printable area on the paper, and printing is performed by driving the nozzle during each reciprocal printing period. To do. For this reason, even if there is an image to be printed only in a part of the entire area, the movement of the IJ head 6n and the drive control operation of the nozzle are performed over the entire area, which is not desirable from the viewpoint of power saving and resource saving. .
Therefore, in the present embodiment, in the oblique printing operation shown in each of the above-described embodiments, an embodiment is shown in which the printing operation is controlled only in a partial region to which an image belonging to only a part of the entire printing region belongs.
In this embodiment, the oblique printing operation control means of the printing control system divides the entire printable image area into partial areas of a predetermined size, and prints only the area where the image is printed in the divided partial areas. An operation is performed that omits an operation related to printing of a region that is an operation control target and is not a control target. In other words, the operation of each of the above embodiments that does not divide the area is performed to eliminate this waste because the print operation becomes wasteful when the image to be printed is localized in a part of the print area.

FIG. 16 is a diagram for explaining an oblique printing operation according to the present embodiment in which the printing operation is performed only in a partial region to which an image in only a part of the entire printing region belongs.
In FIG. 16, a broken line marked on the sheet represents a virtual line for dividing the area. “R”, which is an image to be printed, represents that printing is performed in a limited partial area. Further, the IJ head 6n represents a relative movement from position Z → position A → position B → position C → position D on the sheet in the oblique printing operation process.
In the present embodiment, the oblique printing operation that is performed by limiting a printing area in which an image to be printed is limited is based on the basic operation described in the first embodiment.

In this oblique printing operation, as in the first embodiment, the printing timing, that is, the printing timing, that is, the printing speed, i.e., depending on the moving speed of the IJ head 6n from the printing area end to the end in the main scanning direction and the paper conveyance speed in the sub scanning direction. Determine the nozzle drive control timing.
However, in the present embodiment, the entire print area is divided (for example, 9 divisions in FIG. 16), and the oblique printing operation when printing in each divided area is controlled. Need. This function is a function that is not provided in the first embodiment for performing a basic operation without dividing an area, and will be described below.

The function of controlling the oblique printing operation for each divided partial area (hereinafter referred to as “divided area”) according to the present embodiment is predetermined as 9 divided areas as shown in FIG. 16 before starting the printing operation. It is detected which area of the divided area the image to be printed belongs to.
According to this detection result, the printing operation is performed by operating the nozzle of the IJ head 6n in the divided area to which the image to be printed belongs.
At this time, in the example of FIG. 16, the IJ head 6n at the initial position Z moves in the forward path, and the nozzle is operated for the first time at the position A that reaches the divided area to which the print target image “R” belongs. Therefore, the nozzle is not operated between the position Z and the position A.
In addition, the nozzle operation is stopped and the movement to the IJ head 6n in the main scanning direction is stopped at a position B that passes through the divided area to which “R” belongs and reaches the divided area where there is no image to be printed. The stop operation at the position B is a stop condition that there is no image to be printed even in the divided area on the return path that is turned back after the current forward path, so this condition is confirmed.

After the stop of the IJ head 6n at the position B, the operation of the IJ head 6n is performed again because the divided area (the divided area to which "R" belongs in the return path when the oblique printing operation is performed on the entire print area. ). That is, after the paper that is always conveyed in the sub-scanning direction reaches a position corresponding to the divided area portion on the return path, the IJ head 6n is moved to start the printing operation for operating the nozzles. This is because it is assumed that the relationship between the paper velocity Vs in the sub-scanning direction and the moving velocity Vm of the IJ head 6n in the main scanning direction is maintained in a predetermined relationship that satisfies the oblique printing operation condition.
In the present embodiment, the sheet speed Vs is always constant while the entire sheet is printed, so the relationship between the sheet speed Vs and the moving speed Vm is also maintained constant. Therefore, the time required for printing is the same as in the first embodiment.
The above-described operation of the IJ head 6n that turns back at the position B is also performed after a predetermined waiting time in the turning back of the position C and the position D in the oblique printing operation performed through the position B → the position C → the position D.

As described above, in this embodiment, the entire image area is divided into areas of a predetermined size on the premise that the sub-scanning speed and the main scanning speed, which are the conditions for the oblique printing operation, are maintained. The oblique printing operation is performed so as to omit the operation of the divided areas that do not require printing.
By doing so, in the movement of the IJ head 6n and the driving of the nozzle, it is possible to save power and resources by eliminating unnecessary operations, and to simplify processing necessary for controlling the oblique printing operation. Resources used for data processing can be saved.

“Embodiment 6”
In the present embodiment, the entire printable area of the paper is targeted in the oblique printing operations shown in the first to fourth embodiments, but is limited to a partial area to which an image in only a part of the entire print area belongs. Thus, this embodiment is the same as the fifth embodiment in that it is controlled to perform the printing operation.
Further, in this embodiment, the oblique printing operation control means of the printing control system divides the entire printable image area into areas of a predetermined size, and only the area where the image is printed out of the divided image areas. An operation that is a control target of the print operation and that omits the operation related to the printing of the area that is not the control target is performed. That is, the operation of the above-described embodiment that does not divide the region is performed to eliminate the waste because the waste of the print operation increases when the image to be printed is localized in a part of the region. This is also the same as the fifth embodiment.
However, in the present embodiment, the waiting time when the IJ head 6n moving in the main scanning direction described in the fifth embodiment returns the return path is shortened, and the printing productivity is increased. Therefore, the main scanning direction speed Vm and the sub-scanning direction speed Vs, which are set as operating conditions during the waiting time, are changed to increase.

FIG. 17 is a diagram for explaining an oblique printing operation according to the present embodiment in which the printing operation is performed only in a partial region to which an image belonging to only a part of the entire printing region belongs.
In FIG. 17, a broken line marked on the paper represents a virtual line for dividing the area. “R”, which is an image to be printed, represents that printing is performed in a part of the divided areas. Further, the IJ head 6n represents a relative movement from position Z → position A → position B → position C → position D on the sheet in the oblique printing operation process.
In the present embodiment, the oblique printing operation performed by limiting a certain divided area of the print target image is a mode performed based on the basic operation shown in the first embodiment.

In the present embodiment, in a divided area where an image to be printed is present, similarly to the first embodiment, the moving speed of the IJ head 6n from the end of the print area in the main scanning direction and the conveyance of the paper in the sub-scanning direction. The printing timing, that is, the nozzle drive control timing is determined by the speed.
However, in this embodiment, the entire printing area is divided (for example, 9 divisions in FIG. 17), and the oblique printing operation when printing in each divided area is controlled. Need. This function is a function that is not provided in the first embodiment for performing a basic operation without dividing an area, and will be described below.

The function of controlling the oblique printing operation for each divided area according to the present embodiment is such that, before starting the printing operation, as shown in FIG. Is detected.
According to this detection result, the printing operation is performed by operating the nozzle of the IJ head 6n in the divided area to which the image to be printed belongs.
At this time, in the example of FIG. 17, the IJ head 6n at the initial position Z moves in the forward path, and the printing operation is started by operating the nozzles for the first time at the position A reaching the divided area to which the print target image “R” belongs. Therefore, the nozzle is not operated between the position Z and the position A.
In addition, the nozzle operation is stopped and the movement to the IJ head 6n in the main scanning direction is stopped at a position B that passes through the divided area to which “R” belongs and reaches the divided area where there is no image to be printed. The stop operation at the position B is a stop condition that there is no image to be printed even in the divided area on the return path that is turned back after the current forward path, so this condition is confirmed.

  After the stop of the IJ head 6n at the position B, the operation of the IJ head 6n is performed again because the divided area (the divided area to which "R" belongs in the return path when the oblique printing operation is performed on the entire print area. ). That is, after the paper that is always conveyed in the sub-scanning direction reaches a position corresponding to the divided area portion on the return path, the IJ head 6n is moved to start the printing operation for operating the nozzles. This is because it is assumed that the relationship between the paper velocity Vs in the sub-scanning direction and the moving velocity Vm of the IJ head 6n in the main scanning direction is maintained in a predetermined relationship that satisfies the oblique printing operation condition.

It is a problem to be solved by the present invention to reduce the waiting time until the above-mentioned paper reaches a position corresponding to the divided area portion in the return path. In the present embodiment, in order to reduce the above-mentioned waiting time, Speed up Vs. Further, it is necessary to satisfy the oblique printing operation condition, and the moving speed Vm is also increased in accordance with the predetermined relationship between the sheet speed Vs and the moving speed Vm of the IJ head 6n. As described above, the moving speed Vm and the paper speed Vs of the IJ head 6n are determined in a relationship satisfying the oblique printing operation condition, and the operation of the IJ head 6n is stopped at the position B by changing the instruction of the oblique coefficient. The operation of the IJ head 6n that resumes folding can be performed without any trouble.
The above-described operation of the IJ head 6n that turns back at the position B is also performed by shortening the waiting time in the turning back of the position C and the position D in the oblique printing operation performed through the position B → the position C → the position D.

As described above, in this embodiment, the entire image area is divided into areas of a predetermined size on the premise that the sub-scanning speed and the main scanning speed, which are the conditions for the oblique printing operation, are maintained. The oblique printing operation is performed so as to omit the operation of the divided areas that do not require printing.
By doing so, in the movement of the IJ head 6n and the driving of the nozzle, it is possible to save power and resources by eliminating unnecessary operations, and to simplify processing necessary for controlling the oblique printing operation. Resources used for data processing can be saved.
Further, in the present embodiment, the waiting time caused by omitting the operation of the divided areas is shortened by increasing the moving speed Vm and the paper speed Vs of the IJ head 6n while maintaining the conditions of the oblique printing operation. Printing productivity can be increased.

“Embodiment 7”
In the present embodiment, the entire printing area of the paper is targeted in the oblique printing operations shown in the first to fourth embodiments, but the printing operation is performed only on the partial area to which the image exists in only a part of the entire printing area. It is the same as the fifth and sixth embodiments in that it is an embodiment that controls to perform the above.
However, in the present embodiment, the oblique printing operation control means of the printing control system cuts out the printing target image with as small a number as possible by using a partial area of a predetermined size, and performs an operation for controlling only the cut out area. That is, according to the present embodiment, since the partial area of a predetermined size to which the image belongs is determined to be as small as possible on the basis of the print target image, depending on how the print target image is arranged on the paper, The cutout position of each partial area with respect to is changed. On the other hand, in the fifth and sixth embodiments, since the partial areas are defined by dividing the printable area of the paper into areas of a certain size, the position of each divided area is fixed to the paper.
Therefore, if the size of the partial area to be set is the same, the method employed in the present embodiment reduces the partial area to which the image to be controlled belongs, and the processing load is reduced.

FIG. 18 is a diagram for explaining an oblique printing operation according to the present embodiment in which the printing operation is performed only in a partial region to which an image in only a part of the entire printing region belongs.
In FIG. 18, a broken line marked on a sheet represents a virtual line indicating a partial area determined by cutting out a print target image in the present embodiment. “R”, which is an image to be printed, represents that printing is performed in a partial area. Further, the IJ head 6n represents a relative movement from position Z → position A → position B → position C → position D on the sheet in the oblique printing operation process.

In the present embodiment, the setting of the partial area is as shown by the broken line in FIG. 18, and the image to be printed belongs to one of the partial areas of a predetermined size. Therefore, the operation in units of jobs can be completed only by performing the printing operation in a smaller number of partial areas than in the fifth or sixth embodiment (see FIGS. 16 and 17).
Note that a method of cutting an image to be processed from data handled as a single page image such as page image data by a partial area having a predetermined size is existing image processing. Therefore, the print control system is provided with this existing image processing function, so that the partial area can be set and the oblique print operation of this embodiment can be performed.
Further, the oblique printing operation performed only in the partial region to which the print target image belongs can be performed in the same manner as described in the fifth or sixth embodiment. Therefore, the above description is referred to and the description is omitted here.

As described above, in the present embodiment, as in the above-described fifth or sixth embodiment, the printing operation is performed only on the partial area to which the image exists in only a part of the entire printing area, and the operation of the partial area that does not require printing. The diagonal printing operation is performed so as to eliminate the above. By doing so, in the movement of the IJ head 6n and the driving of the nozzle, it is possible to save power and resources by eliminating unnecessary operations, and to simplify processing necessary for controlling the oblique printing operation. The advantage of saving resources used for data processing is obtained.
In addition, when performing a printing operation only on a partial area to which an image in only a part of the entire print area belongs, a print target image is cut out as few as possible with a partial area of a predetermined size, and only the cut out area is controlled. The operation is performed. By doing so, it is possible to further reduce the number of partial areas to be controlled in the printing operation as compared with the fifth or sixth embodiment, so that the above-described merit can be further increased.

  DESCRIPTION OF SYMBOLS 1 ... CTL board, 2 ... SoC, 3 ... ROM, 4 ... DRAM, 5 ... Head driver, 6, 6n ... IJ head, 8 ... Head motor, 10. ..Paper transport motor, 12 ... encoder.

JP 2004-338215 A

Claims (10)

Original image data having conveying means for conveying the recording medium in the sub-scanning direction and moving means for moving in the main scanning direction an inkjet head having nozzle rows in which nozzles for ejecting ink droplets are arranged at regular intervals in the sub-scanning direction; The nozzles are operated in synchronism with the movement of the ink jet head using the ejection control data generated based on the above, and the pixel groups arranged in the main and sub scanning directions are printed on the recording medium by the ink ejected from the nozzles. An image forming apparatus that
Head movement control means for controlling the moving means to move the inkjet head at a predetermined constant speed during a printing period;
A recording medium conveyance control means for controlling the conveyance means so that the recording medium can be conveyed at a predetermined constant speed and oblique printing can be performed in the printing period;
In accordance with the relationship of the recording medium conveyance speed with respect to the movement speed of the inkjet head determined to print the pixel groups arranged in the main and sub scanning directions, the head movement control means and the recording medium conveyance control means are operated, An oblique printing operation control means for operating the nozzles of the inkjet head based on the ejection control data for oblique printing used for each pixel constituting the pixel group in the printing period;
Pixels arranged in the main and sub scanning directions as ejection control data used to print the reproduced image of the original image on the stationary recording medium by controlling the movement of the inkjet head by the head movement control means Image processing means for creating a data group from the original image data;
An image forming apparatus comprising: discharge control data adjusting means for adjusting discharge control data created by the image processing means as oblique print operation control data used in the oblique print operation control means. The image forming apparatus according to claim 1,
The discharge control data adjusting means performs sub-scanning by increasing the shift amount by one pixel at a time in the printing timing with respect to the pixel row data arranged in the sub-scanning direction in the data group created as discharge control data by the image processing means. Adjustment to the discharge control data for oblique printing by the shift adjustment operation in the scanning direction,
The image forming apparatus, wherein the oblique printing operation control means uses, at each printing timing, ejection control data for oblique printing composed of pixel row data adjusted by the ejection control data adjusting means. The image forming apparatus according to claim 1 or 2,
An image forming apparatus that employs a mechanism that repeats reciprocation by reversal switching in the main scanning direction as the moving means of the ink jet head, and causes the head movement control means to perform the operation during the printing period in each reciprocation. The image forming apparatus according to any one of claims 1 to 3,
The oblique printing operation control means subdivides a printing area corresponding to an initially determined resolution, and prints a group of pixels arranged in the main and sub scanning directions in a printing period provided for each subdivision area. An image forming apparatus that operates the head movement control unit and the recording medium conveyance control unit to increase the resolution, and operates the nozzles of the inkjet head during the printing period. The image forming apparatus according to claim 4.
The oblique printing operation control unit is an image forming apparatus that performs subdivision of the printing area in at least one of a sub-scanning direction and a main scanning direction. The image forming apparatus according to claim 4 or 5,
An operation means for performing an operation for instructing from the outside the resolution of an image to be formed by oblique printing on the recording medium;
The oblique printing operation control means divides the unit printing area into a number corresponding to the resolution instructed by the operation means. The image forming apparatus according to any one of claims 1 to 6,
The oblique printing operation control means divides the entire printable image area into areas of a predetermined size, and performs an operation for controlling only an area where an image is printed out of the divided image areas. . The image forming apparatus according to any one of claims 1 to 6,
The oblique printing operation control means is an image forming apparatus that cuts out an image to be printed in as small a number as possible with an area of a predetermined size, and performs an operation for controlling only the cut out area. The image forming apparatus according to any one of claims 1 to 8,
The oblique printing operation control means detects an inclination error that appears due to conditions inherent in the apparatus when the inkjet head is obliquely moved relative to the recording medium in an oblique printing operation. An image forming apparatus comprising means for correcting by adjusting a control target value of a predetermined speed in the medium conveyance control means. Original image data having conveying means for conveying the recording medium in the sub-scanning direction and moving means for moving in the main scanning direction an inkjet head having nozzle rows in which nozzles for ejecting ink droplets are arranged at regular intervals in the sub-scanning direction; The nozzles are operated in synchronism with the movement of the ink jet head using the ejection control data generated based on the above, and the pixel groups arranged in the main and sub scanning directions are printed on the recording medium by the ink ejected from the nozzles. An image forming method in an image forming apparatus,
According to the relationship of the conveyance speed of the recording medium to the movement speed of the inkjet head determined to print the pixel groups arranged in the main and sub scanning directions, the inkjet head is moved at a predetermined constant speed during the printing period, Control is performed so that oblique printing can be performed by conveying the recording medium at a predetermined constant speed, and the nozzles of the inkjet head are controlled by ejection control data for oblique printing used for each pixel constituting the pixel group in the printing period. An oblique printing operation control process to be operated;
A configuration in which the ink jet head is controlled to move at a predetermined constant speed, and is arranged in the main and sub scanning directions as ejection control data used to print the reproduced image of the original image on the stationary recording medium. An image processing step for creating a pixel data group from the original image data;
An image forming method comprising: an ejection control data adjustment step of adjusting the ejection control data created in the image processing step as the oblique printing operation control data used in the oblique printing operation control step.

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