JP2015221583A - Image forming apparatus, program and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce bi-directional color difference with a simple configuration.SOLUTION: A second black head 4k2 is disposed to have displacement equal to one nozzle row width in a sub-scanning direction in a downstream side of a medium conveying direction with respect to a first color head 4c1 and a second color head 4c2. After an image is formed in main scanning in one direction by the first color head 4c1 and the second color head 4c2, a paper sheet 10 is conveyed for one line. On the image formed in the main scanning in one direction by the first color head 4c1 and the second color head 4c2, an image is formed in the main scanning in another direction by the second black head 4k2 while ejecting black liquid, thereby, the image is completed.

Description

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

  As an image forming apparatus such as a printer, a facsimile, a copying machine, a plotter, or a complex machine of these, for example, a liquid discharge recording type image forming using a recording head composed of a liquid discharge head (droplet discharge head) that discharges ink droplets. As an apparatus, an ink jet recording apparatus or the like is known. This liquid discharge recording type image forming apparatus means that ink droplets are transported from a recording head (not limited to paper, including OHP, and can be attached to ink droplets and other liquids). Yes, it is also ejected onto a recording medium or a recording medium, recording paper, recording paper, etc.) to form an image (recording, printing, printing, and printing are also used synonymously). And a serial type image forming apparatus that forms an image by ejecting liquid droplets while the recording head moves in the main scanning direction, and a line type head that forms images by ejecting liquid droplets without moving the recording head There are line type image forming apparatuses using

  In the present application, the “image forming apparatus” of the liquid discharge recording method is an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or the like. In addition, “image formation” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium (simply It also means that a droplet is landed on a medium). “Ink” is not limited to ink, but is used as a general term for all liquids capable of image formation, such as recording liquid, fixing processing liquid, and liquid. DNA samples, resists, pattern materials, resins and the like are also included. In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself.

  In a serial type image forming apparatus, a carriage on which a recording head is mounted is moved and scanned in a main scanning direction, and an image is formed on a sheet by intermittently conveying a sheet as a recording medium. In such an image forming apparatus, if a color image is to be formed by one main scan (one scan), when performing bidirectional printing in which an image is formed by a reciprocating movement of a carriage, the color difference ( Bidirectional color difference) occurs, and since the resolution depends on the nozzle pitch, the dot density becomes coarse and the image quality deteriorates.

  Therefore, conventionally, high resolution is achieved by increasing the black resolution only during color image formation (Patent Documents 1 and 2), and the nozzles that discharge color droplets are shifted in the nozzle arrangement direction. By doing so, there is known a technique for reducing the bidirectional color difference by unifying the landing order in bidirectional printing (Patent Document 3).

  In addition, as a serial type image forming apparatus, a black nozzle row includes a black nozzle row in which a plurality of nozzles for discharging black droplets are arranged, and a color nozzle row in which a plurality of nozzles for discharging color droplets are arranged. Is also known in which the position of one head (one nozzle row) is shifted from the color nozzle row in the sub-scanning direction and downstream in the medium conveyance direction (Patent Document 4).

Japanese Patent Laid-Open No. 2003-025614 JP 2001-260423 A JP 2004-106392 A JP 2010-208164 A

  Various arrangements are known as the head arrangement for reducing the above-described bidirectional color difference. The simplest configuration includes, for example, a plurality of heads that eject droplets of the same color, and K, C, M , Y, M, C, K in reverse order in the same main scanning direction, using different heads in the forward path and return path, and always ejecting droplets in the order of YMCK, the landing order of droplets of each color Is the same for the outbound and inbound trips.

  By adopting such a configuration, the bidirectional color difference is reduced, and since the color that has landed first becomes dominant, black can be landed last and gray quality can be improved. However, in such a configuration, there is a problem that the number of heads increases.

  The present invention has been made in view of the above problems, and an object thereof is to reduce bidirectional color difference with a simple head arrangement.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
One or a plurality of heads having a black nozzle row in which a plurality of nozzles for discharging black droplets are arranged and a color nozzle row in which a plurality of nozzles for discharging color droplets are arranged are mounted in the main scanning direction. A carriage that is moved and scanned by
Conveying means for conveying the recording medium in the sub-scanning direction,
The black nozzle row is arranged with a position shifted downstream in the medium transport direction in the sub-scanning direction with respect to the color nozzle row,
After forming an image by the color nozzle row in the main scanning in one preceding direction,
Relatively moving the recording medium to the next main scanning position;
In the main scanning in the other direction of the subsequent line, the image formed by the black nozzle row is formed on the image formed by the color nozzle row,
A control means for controlling to complete an image for one main scanning region is provided.

  According to the present invention, it is possible to always hit a black droplet after a color droplet with a simple configuration, thereby reducing bidirectional color difference and improving gray quality.

FIG. 2 is an explanatory plan view of a main part of a mechanism unit of the image forming apparatus according to the first embodiment of the present invention. It is side surface explanatory drawing of the mechanism part. FIG. 6 is an explanatory plan view for explaining the head configuration. It is block explanatory drawing which shows the outline | summary of the control part of the apparatus. It is explanatory drawing with which it uses for description of the image formation operation | movement in 1st Embodiment of this invention. It is explanatory drawing with which it uses for description of the head structure in 2nd Embodiment of this invention. It is explanatory drawing with which it uses for description of the head structure in 3rd Embodiment of this invention. (A) is explanatory drawing explaining the 1st example of the example of arrangement | positioning in a subscanning direction of a black nozzle row and a color nozzle row, (b) is the 3rd scan (3rd time) from the 1st scan (1st main scan). FIG. 10 is an explanatory diagram illustrating an image forming process until (main scanning). (A) is explanatory drawing explaining the 2nd example of the example of arrangement | positioning in the subscanning direction of a black nozzle row and a color nozzle row, (b) is the 3rd scan (3rd time) from 1st scan (1st main scan). FIG. 10 is an explanatory diagram illustrating an image forming process until (main scanning). (A) is explanatory drawing explaining the 3rd example of the example of arrangement | positioning in the subscanning direction of a black nozzle row and a color nozzle row, (b) is the 3rd scan (3rd time) from 1st scan (1st main scan). FIG. 10 is an explanatory diagram illustrating an image forming process until (main scanning).

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of an image forming apparatus to which the present invention is applied will be described with reference to FIGS. FIG. 1 is an explanatory plan view of the main part of the mechanism of the image forming apparatus, and FIG. 2 is an explanatory side view of the mechanism.

  This image forming apparatus is a serial type image forming apparatus, and a main scanning rod 5 is slidably held by a main guide rod 1 and a sub guide member (not shown) horizontally mounted between left and right side plates 100L and 100R. Thus, moving scanning is performed in the main scanning direction via the timing belt 8 passed between the driving pulley 6 and the driven pulley 7.

  On the carriage 3, a first black head 4k1, a second black head 4k2, a first color head 4c1, and a second color head 4c2 are mounted. Hereinafter, the first color head 4c1 and the second color head 4c2 are collectively referred to as “color head 4c”, and when the heads are not distinguished from each other, they are referred to as “head 4”.

  As shown in FIG. 3 (a plan view of the transmission state), these heads 4 include two nozzles in which a plurality of nozzles 4n that discharge droplets are arranged in the sub-scanning direction (direction perpendicular to the main scanning direction). It has rows Na and Nb.

  The first black head 4k1 discharges black (K) droplets from the nozzle rows Na and Nb, and discharges yellow (Y) droplets from the nozzle row Na of the first color head 4c1. Magenta (M) droplets are ejected from the nozzle row Nb, cyan (C) droplets are ejected from the nozzle row Na of the second color head 4c2, and the nozzle row Nb is an empty nozzle row (or fixing process). Nozzle row for discharging liquid). The second black head 4k2 ejects black (K) droplets from the nozzle rows Na and Nb.

  As a result, the nozzle density of the first black head 4k1 and the second black head 4k2 are both twice the nozzle density of the first and second color heads 4c1 and 4c2 that discharge color droplets.

  Here, the first black head 4k1, the first color head 4c1, and the second color head 4c2 are arranged side by side in the main scanning direction with the same position in the sub scanning direction. The second black head 4k2 is arranged so that the position corresponding to the width of one nozzle row is shifted downstream of the first black head 4k1, the first color head 4c1, and the second color head 4c2 in the sub-scanning direction in the paper transport direction. Yes. That is, in this embodiment, the second black head 4k2 corresponds to the “black nozzle row” in the present invention, and the first and second color heads 4c1 and 4c2 also correspond to the “color nozzle row”.

  On the other hand, in order to transport the paper, a transport belt 12 is provided as a transport means for electrostatically attracting the paper and transporting the paper at a position facing the recording head 4. The transport belt 12 is an endless belt, is configured to wrap around the transport roller 13 and the tension roller 14 and circulate in the belt transport direction (sub-scanning direction). 15 is charged (charged).

  Further, the conveyance belt 12 rotates in the sub-scanning direction when the conveyance roller 13 is rotationally driven by the sub-scanning motor 16 via the timing belt 17 and the timing pulley 18.

  Further, a maintenance / recovery mechanism 20 that performs maintenance / recovery of the recording head 4 is arranged on the side of the conveyance belt 12 on one side of the carriage 3 in the main scanning direction, and from the head 4 on the side of the conveyance belt 12 on the other side. Empty discharge receptacles 21 for performing empty discharge are respectively disposed.

  The maintenance / recovery mechanism 20 includes, for example, four cap members 31 for capping the nozzle surface (the surface on which the nozzles are formed) of the recording head 4, a wiper member 32 for wiping the nozzle surface, and droplets that do not contribute to image formation ( An empty discharge receiver 33 that receives empty discharge droplets) and the like.

  An encoder scale 23 having a predetermined pattern (also referred to as a position identification portion, a scale, a slit, etc., hereinafter referred to as “slit”) is stretched between both side plates along the main scanning direction of the carriage 3, and the carriage 23 is provided with an encoder sensor 24 composed of a transmissive photosensor that reads the slit of the encoder scale 23, and the encoder scale 23 and the encoder sensor 24 constitute a linear encoder (main scanning encoder) 27 that detects the movement of the carriage 23. ing.

  Further, an encoder scale (code wheel) 25 is attached to the shaft of the transport roller 13, and an encoder sensor 26 composed of a transmission type photosensor for detecting a pattern (slit) formed on the encoder scale 25 is provided. 25 and the encoder sensor 26 constitute a rotary encoder (sub-scanning encoder) 28 for detecting the moving amount and moving position of the conveyor belt 12.

  In this image forming apparatus configured as described above, the sheet 10 is fed from the sheet feeding tray (not shown) onto the charged conveying belt 12 and sucked, and the sheet 10 is moved in the sub-scanning direction by the circular movement of the conveying belt 12. Be transported. Therefore, by driving the recording head 4 according to the image signal while moving the carriage 3 in the main scanning direction, ink droplets are ejected onto the stopped paper 10 to record one line, and the paper 10 is placed in place. After the quantitative transport, record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 10 has reached the recording area, the recording operation is finished, and the paper 10 is discharged onto a paper discharge tray.

Next, an outline of the control unit of the image forming apparatus will be described with reference to FIG. In addition, the figure is a block explanatory drawing of the control part.
The control unit 500 includes a CPU 501 that controls the entire apparatus, various programs including a program according to the present invention that causes the CPU 501 to execute control (processing) related to carriage movement, paper conveyance, and droplet ejection according to the present invention. ROM 502 for storing fixed data, RAM 503 for temporarily storing image data, rewritable nonvolatile memory 504 for holding data even while the apparatus is powered off, and various signal processing for image data And an ASIC 505 for processing input / output signals for controlling the entire apparatus, image processing for rearranging, and the like.

  Further, a print control unit 508 including a data transfer unit for driving and controlling each head 4 and a drive signal generating unit, a head driver (driver IC) 509 for driving each head 4 provided on the carriage 3 side, A main scanning motor 5 that moves and scans the carriage 3, a motor driving unit 510 that drives a sub-scanning motor 16 that moves the conveyor belt 12 circulates, an AC bias supply unit 512 that supplies an AC bias to the charging roller 15, and the like. ing.

  The I / O unit 513 acquires information from the encoder sensor 24 of the main scanning encoder 27, the encoder sensor 26 of the sub scanning encoder 28, and various sensor groups 515 mounted on the apparatus, and is necessary for controlling the printer. This information is extracted and used to control the print control unit 508, the motor drive unit 510, and the AC bias supply unit 511. The sensor group 515 includes an optical sensor for detecting the position of the paper, a thermistor for monitoring the temperature and humidity in the machine, a sensor for monitoring the voltage of the charging belt, an interlock switch for detecting opening and closing of the cover, and the like. The I / O unit 513 can process various sensor information.

  Here, the CPU 501 detects a speed detection value and a position detection value obtained by sampling a detection pulse from the encoder sensor 24 constituting the main scanning encoder 27, and a speed target value and a position obtained from a previously stored speed / position profile. Based on the target value, a drive output value (control value) for the main scanning motor 5 is calculated and the main scanning motor 5 is driven via the motor driving unit 210. Similarly, a speed detection value and a position detection value obtained by sampling a detection pulse from the encoder sensor 25 constituting the sub-scanning encoder 28, and a speed target value and a position target value obtained from a previously stored speed / position profile, Based on this, a drive output value (control value) for the sub-scanning motor 16 is calculated, and the sub-scanning motor 16 is driven via the motor driving unit 211.

  The control unit 500 is connected to an operation panel 514 for inputting and displaying information necessary for the apparatus. Further, the control unit 500 includes a real time clock (RTC) 520 which is a time measuring means for measuring the current time (year / month / day / time).

  The control unit 500 has an I / F 506 for transmitting and receiving data and signals to and from the host side, an information processing device such as a personal computer, an image reading device such as an image scanner, an imaging device such as a digital camera, and the like. From the host 600 side via the cable or network via the I / F 506.

  The CPU 501 of the control unit 500 reads and analyzes the print data in the reception buffer included in the I / F 506, performs necessary image processing, data rearrangement processing, and the like in the ASIC 505, and prints the image data. Section 508 is transferred to the color nozzle row driver 509. Note that generation of dot pattern data for image output is performed by the printer driver 601 on the host 600 side.

  The print control unit 508 transfers the above-described image data as serial data, and outputs a transfer clock, a latch signal, a control signal, and the like necessary for transferring the image data and confirming the transfer to the head driver 509. Including a D / A converter for D / A converting D / A conversion of drive pulse pattern data stored in the ROM, a voltage signal amplifier, a current amplifier, and the like, and a drive signal or a plurality of drive pulses Is output to the head driver 509.

  The head driver 509 selectively selects droplets of the recording head 4 based on image data corresponding to one line of the recording head 4 input serially, and a driving pulse constituting a driving signal provided from the print control unit 508. The recording head 24 is driven by applying it to a driving element (for example, a piezoelectric element) that generates energy to be discharged. At this time, by selecting a drive pulse that constitutes a drive signal, for example, droplets having different droplet sizes, such as large droplets, medium droplets, and small droplets, can be ejected and dots having different sizes can be sorted.

  Further, when the CPU 501 controls each unit by a program stored in the ROM 502 to form an image corresponding to the width of one nozzle row by one scan of the carriage 3, the first and second color heads 4c1, 4c1, The process of ejecting droplets corresponding to the image corresponding to the width of one nozzle array from each nozzle array of 4c2, the process of relatively moving the paper 10 to the next main scanning position, and the second black head 4k2 in the next main scanning A droplet corresponding to an image corresponding to the width of one nozzle row is ejected from each of the nozzle rows to form an image for one nozzle row.

Next, an image forming operation in the first embodiment of the present invention will be described with reference to FIG.
First, in FIG. 5, the forward path of the carriage 3 is set to the right direction, the return path is set to the left direction, and the sheet feeding direction is set from the bottom to the top (the head is relatively headed from top to bottom). An area corresponding to one main scan of the carriage 3 is called “one main scan area”, and an area on the medium corresponding to this is called “one line”. One main scan area, one line in the sub-scan direction The width corresponds to the nozzle row width.

  First, the carriage 3 is main-scanned in the forward direction, the color head 4c is driven to discharge color droplets, and an image for one line is formed on the first line by the color droplets. At this time, the second black head 4k2 is not used because it is disposed on the downstream side in the medium conveyance direction.

  Then, after the image is formed on the first line by the color head 4c for one line, the paper 10 is conveyed by one line. As a result, the color head 4c moves to the second line area, and the second black head 4k2 moves to the first line area.

  Therefore, the carriage 3 is moved in the main scanning direction in the backward direction, the second black head 4k2 is driven to discharge black droplets, and the black color image is formed on the image by the color head 4c formed in the region of the first line. An image is formed by droplets. Thereby, the entire image of one line (one type scanning region) of the first line is completed.

  At the same time, the color head 4c is driven to discharge color droplets, and an image for one line is formed on the second line by the color droplets.

  After the image formation for one line, the paper 10 is conveyed for one line. As a result, the color head 4c moves to the third line area, and the second black head 4k2 moves to the second line area.

  Therefore, the carriage 3 is moved in the main scanning direction in the forward direction, the second black head 4k2 is driven to discharge black droplets, and the black color is formed on the image by the color head 4c formed in the second line area. An image is formed by droplets. As a result, the entire image for one line of the second line is completed.

  At the same time, the color head 4c is driven to discharge color droplets, and an image for one line is formed on the third line by the color droplets.

  In this way, an image is formed by ejecting black droplets by the black head 4k2 in the subsequent main scanning in the other direction on the image formed by the color head 4c in the preceding main scanning in one direction. Now complete the image. In the above example, in the first line and the second line, the main scanning of the first line is the main scanning in one direction, and the main scanning of the second line is the main scanning in the other direction of the subsequent line. In the second line and the third line, the main scanning of the second line is the main scanning in one direction, and the main scanning of the third line is the main scanning in the other direction of the subsequent line. That is, “one direction” and “other direction” mean scanning directions having opposite relations, and do not correspond to the forward path and the backward path.

  As a result, the black droplets are always ejected last by the black head, and because of the liquid penetration characteristics, the droplets that landed later pass the droplets that landed first. Therefore, the bidirectional color difference of gray can be reduced and the quality can be improved.

  Also, by adjusting the position of the black nozzle row or the stop time between the forward pass and the return pass, the landing time of the color and black can be changed, and the gray density and black blurring of the color background can be controlled. . This is because, as described above, the color that landed first becomes dominant, but it is different when it dries, and the permeation characteristics can be changed by changing the drying time of the colored droplets that have been deposited first. by.

  In addition, as described above, when an image is formed by one scan by making the resolution of the black head (black nozzle array) higher than the resolution of the color head (color nozzle array), the image quality of the black image is improved. In the gray expression (when gray is expressed with a colorant other than black and black), since the dots can be finely arranged, the granularity can be lowered.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a schematic explanatory view for explaining the head arrangement in the embodiment.
In the present embodiment, the first black head 4k1 in the first embodiment is not mounted, but one black head 4k is mounted, and the black head 4k is downstream of the color head 4c in the sub-scanning direction in the paper transport direction. The positions corresponding to one nozzle row width are shifted from each other.

  Even if comprised in this way, the effect similar to the said 1st Embodiment can be acquired, and a carriage weight can be reduced by reducing the number of heads.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 7 is a schematic explanatory view for explaining the head arrangement in the embodiment.
In the present embodiment, one black head 44k, which is a combination of the first black head 4k1 and the second black head 4k2 in the first embodiment, is mounted, and this black head 44k has the same sub-scanning position as the color head 4c. And a nozzle row portion 44k2 whose position is shifted by an amount corresponding to the width of one nozzle row on the downstream side in the paper transport direction in the sub-scanning direction with respect to the color head 4c.

  Even with this configuration, by using the nozzle row portion 44k2 of the black head 44k, the same operation and effect as in the first embodiment can be obtained by performing the same operation as in the first embodiment.

  Next, different examples of the arrangement example (head configuration example) of the black nozzle row and the color nozzle row in the sub-scanning direction according to the present invention including the above-described embodiment will be described with reference to FIGS. Each figure (a) is an explanatory diagram for explaining the arrangement relationship of the nozzle rows, and each figure (b) is an image formation from the first scan (first main scan) to the third scan (third main scan). It is explanatory drawing explaining the process of. In addition, the nozzle row is described as 6 nozzles.

  In the first example shown in FIG. 8, as described in the above embodiments, the black nozzle row Bk is one nozzle row (here, equivalent to six nozzles) with respect to the color nozzle row C, downstream in the sub-scanning direction. This is an example in which they are shifted to each other. In this first example, the transport amount of the recording medium is equivalent to 6 nozzles in each scan.

  In other words, the color nozzle array C is used in the first scan (one-direction scan) to complete an image of only six nozzles. Thereafter, the recording medium is conveyed by 6 nozzles, and in the second scan (scan in the other direction), black droplets are formed on the color-only image completed in the first scan using the black nozzle row Bk. An image is completed by discharging, and a color-only image for the next six nozzles is completed using the color nozzle row C. Thereafter, the recording medium is transported by 6 nozzles, and in the third scan (scan in one direction), black (K) is printed using the black nozzle row Bk on the color-only image completed in the second scan. An image is completed by discharging droplets, and an image of only the next 6 nozzles is completed using the color nozzle array C.

  The second example shown in FIG. 9 is an example in which the black nozzle row Bk is shifted from the color nozzle row C by an amount equivalent to two nozzles on the downstream side in the sub-scanning direction. In this second example, the conveyance amount of the recording medium is as follows: 6 nozzle equivalent → 4 nozzle equivalent → 6 nozzle equivalent → 4 nozzle equivalent.

  In other words, the color nozzle array C is used in the first scan (one-direction scan) to complete an image of only six nozzles. Thereafter, the recording medium is transported by 6 nozzles, and in the second scan (scan in the other direction), the black nozzle array Bk is used on the color-only image completed in the first scan, and the black nozzle array Bk is used. An image is completed by ejecting liquid droplets, and four nozzles that do not overlap with the black nozzle row Bk in the color nozzle row C (not overlapping in the main scanning direction) are used. Complete the image. Thereafter, the recording medium is conveyed by 4 nozzles, and in the third scan (scan in one direction), the color in the black nozzle row Bk is formed on the color-only image of 4 nozzle rows completed in the second scan. Using four nozzles that do not overlap with the nozzle row C (not overlapping in the main scanning direction), black droplets are ejected to complete the image for the four nozzle rows, and the color nozzle row C is used. Complete the color-only image for the next 6 nozzles

  The third example shown in FIG. 10 is an example in which the black nozzle row Bk is shifted from the color nozzle row C by an amount equivalent to 5 nozzles on the downstream side in the sub-scanning direction. In this third example, the conveyance amount of the recording medium is as follows: 6 nozzle equivalent → 1 nozzle equivalent → 6 nozzle equivalent → 1 nozzle equivalent.

  In other words, the color nozzle array C is used in the first scan (one-direction scan) to complete an image of only six nozzles. Thereafter, the recording medium is transported by 6 nozzles, and in the second scan (scan in the other direction), the black nozzle array Bk is used on the color-only image completed in the first scan, and the black nozzle array Bk is used. An image is completed by ejecting liquid droplets, and only one color for one nozzle is used by using one nozzle that does not overlap with the black nozzle row Bk in the color nozzle row C (does not overlap in the main scanning direction). Complete the image. Thereafter, the recording medium is conveyed by one nozzle, and in the third scan (scan in one direction), the color in the black nozzle row Bk is formed on the color-only image of one nozzle row completed in the second scan. Using one nozzle that does not overlap with nozzle row C (not overlapping in the main scanning direction), black droplets are ejected to complete an image for one nozzle row, and color nozzle row C is used. Complete the color-only image for the next 6 nozzles

  As described above, the shift amount in the sub-scanning direction between the black nozzle row and the color nozzle row can be selected in a range corresponding to one nozzle in one nozzle row or equivalent to all nozzles.

  In each of the above embodiments, the black nozzle row and the color nozzle row are each constituted by a black head and a plurality of color heads. However, if the positional relationship of the nozzle rows is as described above, all are constituted as one head. You can also.

  Further, the above-described processing relating to image formation is performed by a computer by a program, and this program can be provided by being stored in a storage medium, or can be provided by downloading through a network such as the Internet. The image forming system can also be configured by combining the image forming apparatus described in the above embodiment and the host side (information processing apparatus).

DESCRIPTION OF SYMBOLS 1 Guide rod 3 Carriage 4k1 1st black head 4k2 2nd black head (black nozzle row)
4c1 1st color head (color nozzle row)
4c2 Second color head (color nozzle row)
500 Control unit

In order to solve the above problems, an image forming apparatus according to the present invention provides:
One or a plurality of heads having a black nozzle row in which a plurality of nozzles for discharging black droplets are arranged and a color nozzle row in which a plurality of nozzles for discharging color droplets are arranged are mounted in the main scanning direction. A carriage that is moved and scanned by
Conveying means for conveying the recording medium in the sub-scanning direction,
The black nozzle row is disposed at the same position in the sub-scanning direction with respect to the color nozzle row and the portion arranged in the sub-scanning direction downstream of the color nozzle row in the medium transport direction. Including parts,
After forming an image by the color nozzle row in the main scanning in one preceding direction,
Distance fraction do not overlap in the black nozzle and the sub-scanning direction and the color nozzle array, relatively to move the recording medium,
In the main scanning in the other direction of the subsequent line, the nozzles of the color nozzle row that overlap in the sub-scanning direction between the color nozzle row and the black nozzle row are not used for image formation. The image formed by the black nozzle row is formed on the image formed in
Complete the image for one scanning area,
Control for forming an image with the nozzles of the color nozzle row of the color nozzle row and the black nozzle row that do not overlap in the sub-scanning direction when performing the main scanning in the other direction of the subsequent line. It was set as the structure provided with the means.

Claims (6)

One or a plurality of heads having a black nozzle row in which a plurality of nozzles for discharging black droplets are arranged and a color nozzle row in which a plurality of nozzles for discharging color droplets are arranged are mounted in the main scanning direction. A carriage that is moved and scanned by
Conveying means for conveying the recording medium in the sub-scanning direction,
The black nozzle row is arranged with a position shifted downstream in the medium transport direction in the sub-scanning direction with respect to the color nozzle row,
After forming an image by the color nozzle row in the main scanning in one preceding direction,
Relatively moving the recording medium to the next main scanning position;
In the main scanning in the other direction of the subsequent line, the image formed by the black nozzle row is formed on the image formed by the color nozzle row,
An image forming apparatus comprising control means for controlling completion of an image for one scanning region. Having first and second black nozzle rows in which a plurality of nozzles for discharging the black droplets are arranged;
The first black nozzle row is arranged with the same position in the sub-scanning direction as the color nozzle row,
2. The image forming apparatus according to claim 1, wherein the second black nozzle row is arranged at a position shifted downstream of the color nozzle row in the sub-scanning direction in the medium transport direction.   The black nozzle row is disposed at the same position in the sub-scanning direction with respect to the color nozzle row and the portion arranged in the sub-scanning direction downstream of the color nozzle row in the medium transport direction. The image forming apparatus according to claim 1, further comprising a portion.   The image forming apparatus according to claim 1, wherein a density of an image formed by the black nozzle row is higher than a density of an image formed by the color nozzle row. One or a plurality of heads having a black nozzle row in which a plurality of nozzles for discharging black droplets are arranged and a color nozzle row in which a plurality of nozzles for discharging color droplets are arranged are mounted in the main scanning direction. A carriage that is moved and scanned by
Conveying means for conveying the recording medium in the sub-scanning direction,
The black nozzle row is a program for causing a computer to perform a process of controlling an image forming operation by an image forming apparatus arranged with a position shifted downstream in the medium transport direction in the sub-scanning direction with respect to the color nozzle row. ,
After forming an image by the color nozzle row in the main scanning in one preceding direction,
Relatively moving the recording medium to the next main scanning position;
In the main scanning in the other direction of the subsequent line, the image formed by the black nozzle row is formed on the image formed by the color nozzle row,
A program for performing a process of controlling to complete an image for one main scanning region. One or a plurality of heads having a black nozzle row in which a plurality of nozzles for discharging black droplets are arranged and a color nozzle row in which a plurality of nozzles for discharging color droplets are arranged are mounted in the main scanning direction. A carriage that is moved and scanned by
Conveying means for conveying the recording medium in the sub-scanning direction,
The black nozzle row is an image forming method by an image forming apparatus arranged with a position shifted downstream in the medium transport direction in the sub-scanning direction with respect to the color nozzle row,
After forming an image by the color nozzle row in the main scanning in one preceding direction,
Relatively moving the recording medium to the next main scanning position;
In the main scanning in the other direction of the subsequent line, the image formed by the black nozzle row is formed on the image formed by the color nozzle row,
An image forming method comprising: completing an image for one main scanning region.

Images