JP2013216073A - Apparatus and method of forming image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent landing of liquid on an object other than a medium.SOLUTION: An image forming apparatus includes: a nozzle row where a plurality of nozzles that discharge liquid are arranged in a predetermined direction; flags for clipping in which either the discharge is effective or the discharge is invalid is set for each nozzle of the nozzle row; and a control part that forms an image on a medium by doing a dot formation operation to discharge the liquid from the nozzles, while moving nozzle rows and the medium relatively to an intersection direction that intersects a predetermined direction based on the image data, wherein the control part prohibits discharge of the liquid from the nozzle of which flag is the discharge is invalid regardless of the image data in the dot formation operation.

Description

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

  As an image forming apparatus, an ink jet printer that forms an image by ejecting ink (a kind of liquid) from a head is known. Such a printer head is provided with a nozzle row in which a plurality of nozzles for ejecting ink are arranged in a predetermined direction. An image is formed on the medium by intermittently ejecting ink from each nozzle row of the head while relatively moving the head and the medium in a direction intersecting the predetermined direction (intersection direction).

JP 2007-68202 A

In the printer as described above, the mounting position of the head may be shifted due to individual differences between apparatuses. Further, when the medium is transported, a phenomenon called meandering (also referred to as skew or skew) in which the medium is transported obliquely with respect to the transport direction (for example, the crossing direction) may occur. In such a case, the ink ejected from each nozzle in the nozzle row may not land on the medium and may land on a medium other than the medium (for example, a platen). When ink lands on the platen, the medium passing over the platen is then stained with ink.
Also, a plurality of label images may be formed in a direction that intersects the transport direction on the medium using the printer as described above. In such a case, if the meandering as described above occurs, the ink constituting the label image may not land on the medium completely, and a part thereof may be missing, resulting in an incomplete label image. Therefore, such an incomplete image is regarded as a defective product, and the inspection process for distinguishing it from the above-described non-defective product is time consuming and an efficient label image cannot be produced.
Accordingly, an object of the present invention is to prevent the landing of liquid on a medium other than the medium and to enable efficient production of a label image.

The main invention for achieving at least a part of the above object is:
A nozzle row in which a plurality of nozzles for discharging liquid are arranged in a predetermined direction;
A clipping flag in which either ejection valid or ejection invalid is set for each nozzle of the nozzle row, and
Control for forming an image on the medium by performing a dot forming operation of ejecting the liquid from each nozzle while moving the nozzle array and the medium in a crossing direction intersecting the predetermined direction based on image data A controller that prohibits the discharge of the liquid from the nozzles whose discharge is disabled during the dot forming operation regardless of the image data;
An image forming apparatus comprising:

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

1 is a block diagram of the overall configuration of a printer. FIG. 3 is a schematic view around a print area. It is explanatory drawing of an example of nozzle arrangement | positioning of each head. 4A to 4C are explanatory diagrams of the relationship between the timing of UV irradiation in temporary curing and the shape of UV ink (dots). It is a flowchart of the printing process by the printer 1 of this embodiment. It is explanatory drawing when the attachment position of a head is normal. It is explanatory drawing when a head is inclined and attached with respect to the paper width direction. It is explanatory drawing of the dot formation operation | movement in this embodiment. It is a flowchart which shows the setting method of a flag. It is explanatory drawing of the dot formation operation | movement in a modification. It is a flowchart which shows the flag setting method of 2nd Embodiment. It is a block diagram of the whole structure of the printer 1 of 3rd Embodiment. FIG. 13A is a schematic cross-sectional view of the printer 1 of the third embodiment, and FIG. 13B is a schematic top view of the printer 1 of the third embodiment. It is a figure which shows arrangement | positioning of the some head 31 in the head unit 30 of 3rd Embodiment. It is a figure for demonstrating the correction method of the dot formation position of a comparative example. It is a figure which shows a mode that the head unit 30 of 3rd Embodiment inclines during the movement to a conveyance direction. FIG. 17A is a diagram showing a test pattern formed by the head unit 30 that is tilted during movement in the transport direction, and FIG. 17B shows a line corrected by the correction method of the comparative example based on the test pattern result of FIG. 17A. FIG. It is a figure which shows the test pattern formed by 3rd Embodiment. It is a figure which shows an example of the image formed in 4th Embodiment.

At least the following matters will become clear from the description of the present specification and the accompanying drawings.
A nozzle row in which a plurality of nozzles for discharging liquid are arranged in a predetermined direction;
A clipping flag in which either ejection valid or ejection invalid is set for each nozzle of the nozzle row, and
Control for forming an image on the medium by performing a dot forming operation of ejecting the liquid from each nozzle while moving the nozzle array and the medium in a crossing direction intersecting the predetermined direction based on image data A controller that prohibits the discharge of the liquid from the nozzles whose discharge is disabled during the dot forming operation regardless of the image data;
An image forming apparatus characterized by comprising:
According to such an image forming apparatus, liquid is not ejected from the nozzles whose flag is set to ejection invalidity regardless of the image data. Therefore, it is possible to prevent the liquid from landing on the medium other than the medium by setting this flag.

In this image forming apparatus, it is preferable that a test pattern is formed on the medium before the image is formed, and the flag is set for each nozzle based on the result of reading the test pattern.
According to such an image forming apparatus, it is possible to prevent the liquid from landing on the medium other than the medium regardless of the mounting accuracy of the nozzle row of each apparatus.

In this image forming apparatus, the medium is supported, and is provided on the upstream side of the transport path of the medium from the nozzle array, and a support unit that faces the nozzle array through the medium, and detects the medium Preferably, the flag corresponding to the nozzle that discharges the liquid to the support portion is disabled based on the detection result of the detection sensor.
According to such an image forming apparatus, it is possible to perform control so that liquid does not land on the support portion at high speed.

In such an image forming apparatus, it is preferable that control information different from the flag and for controlling the liquid ejection timing is provided for each nozzle.
According to such an image forming apparatus, it is possible to reduce variations in the landing position of the liquid due to the nozzle rows being provided obliquely with respect to the paper width direction or the meandering of the medium.

In this image forming apparatus, the control unit reciprocates the nozzle row in one direction side and the other direction side in the intersecting direction during the dot forming operation, and the flag and the control information are It is desirable that the nozzle row is set for each of the case where the nozzle row moves in the one direction and the case where the nozzle row moves in the other direction.
According to such an image forming apparatus, it is possible to reduce the landing position deviation with respect to each of the case where the nozzle row moves to one side and the case where the nozzle row moves to the other side.

In this image forming apparatus, the image data is formed by arranging a plurality of images in the predetermined direction of the medium using each nozzle of the nozzle row, and the control unit forms a certain image. In the case where the discharge invalid flag is set for the nozzle to perform, it is preferable that the certain image of the plurality of images is not formed regardless of the image data.
According to such an image forming apparatus, ink consumption can be reduced. Further, it is possible to manufacture an efficient label image.

An image forming method for forming an image on a medium by an image forming apparatus including a nozzle row in which a plurality of nozzles for discharging liquid are arranged in a predetermined direction,
For each nozzle in the nozzle row, setting a clipping flag indicating either ejection valid or ejection invalid,
Performing a dot forming operation of ejecting the liquid from each nozzle while relatively moving the nozzle row and the medium in a crossing direction crossing the predetermined direction based on image data;
During the dot forming operation, the discharge of the liquid is prohibited regardless of the image data from a nozzle whose flag is invalid.
An image forming method characterized by having:

  In the following embodiments, an ink jet printer (hereinafter also referred to as a printer 1) will be described as an example of the image forming apparatus.

=== First Embodiment ===
<About printer configuration>
FIG. 1 is a block diagram of the overall configuration of the printer 1. FIG. 2 is a schematic view around the print area.
The printer 1 is a printing device that prints an image on a medium such as paper, cloth, or film, and is communicably connected to a computer 110 that is an external device.

A printer driver is installed in the computer 110. The printer driver is a program for displaying a user interface on a display device (not shown) and converting image data output from an application program into print data. This printer driver is recorded on a recording medium (computer-readable recording medium) such as a flexible disk FD or a CD-ROM. Alternatively, the printer driver can be downloaded to the computer 110 via the Internet. In addition, this program is comprised from the code | cord | chord for implement | achieving various functions.
Then, the computer 110 outputs print data corresponding to the image to be printed to the printer 1 in order to cause the printer 1 to print an image.

  The printer 1 of the present embodiment is an apparatus that prints an image on a medium by ejecting ultraviolet curable ink (hereinafter, UV ink) that is cured by irradiation with ultraviolet light (hereinafter, UV) as an example of a liquid. The UV ink is an ink containing an ultraviolet curable resin, and is cured by undergoing a photopolymerization reaction in the ultraviolet curable resin when irradiated with UV. Note that the printer 1 of the present embodiment prints an image using four colors of UV ink (color ink) of cyan, magenta, yellow, and black.

  The printer 1 includes a transport unit 20, a head unit 30, an irradiation unit 40, a detector group 50, and a controller 60. The printer 1 that has received print data from the computer 110 that is an external device controls each unit (the transport unit 20, the head unit 30, and the irradiation unit 40) by the controller 60, and prints an image on a medium according to the print data. The controller 60 controls each unit based on the print data received from the computer 110 and prints an image on a medium. The situation in the printer 1 is monitored by the detector group 50, and the detector group 50 outputs the detection result to the controller 60. The controller 60 controls each unit based on the detection result output from the detector group 50.

  The transport unit 20 is for transporting a medium (for example, paper S) in the transport direction. In the present embodiment, the transport direction is a direction that intersects the direction in which the nozzles of the nozzle row of the head unit 30 are arranged (nozzle row direction). That is, the transport direction corresponds to the cross direction. The transport unit 20 includes an upstream transport roller 21 </ b> A, a downstream transport roller 21 </ b> B, and a transport drum 22.

  The upstream side conveyance roller 21 </ b> A is provided at the lower left position in the drawing with respect to the conveyance drum 22. Further, the downstream side conveyance roller 21 </ b> B is provided at a position lower than the conveyance drum 22 in the gravity direction and away from the conveyance drum 22. As the upstream-side transport roller 21A and the downstream-side transport roller 21B rotate, the medium is transported and the transport drum 22 rotates.

  The transport drum 22 is a cylindrical transport member, and supports the long paper S wound in a roll shape on the peripheral surface and transports it in the transport direction. Further, the transport drum 22 faces each head via the paper S. That is, the transport drum 22 corresponds to a support portion. As shown in FIG. 2, the radius R of the conveyance drum 22 is larger than the radius r of each conveyance roller (upstream conveyance roller 21A, downstream conveyance roller 21B).

  The paper S is supplied from an upstream paper feed roll (not shown) and taken up by a downstream take-up roller (not shown). Further, the paper S is transported so as to be in close contact with the transport drum 22 with a predetermined tension.

  The head unit 30 is for ejecting UV ink onto a medium. The head unit 30 forms dots on the medium by ejecting ink from each head onto the medium being transported, and prints an image on the medium. Note that each head of the head unit 30 of the printer 1 of the present embodiment can form dots for the medium width at a time. In this embodiment, four color inks for forming an image are used as the UV ink. As shown in FIG. 2, in order from the upstream side in the transport direction, a black ink head K that ejects black UV ink, a cyan ink head C that ejects cyan UV ink, and a magenta ink head M that ejects magenta UV ink. The yellow ink heads Y that discharge yellow UV ink are provided so as to face the peripheral surface of the transport drum 22. Details of the configuration of the head unit 30 will be described later.

  The irradiation unit 40 irradiates UV toward the UV ink that has landed on the medium. The dots formed on the medium are cured by receiving UV irradiation from the irradiation unit 40. The irradiation unit 40 of the present embodiment includes provisional curing irradiation units 42 a to 42 d and a main curing irradiation unit 44.

  The pre-curing irradiation units 42a to 42d irradiate UV for pre-curing the dots formed on the medium. The provisional curing irradiation unit 42 a is provided on the downstream side in the transport direction of the black ink head K, and the provisional curing irradiation unit 42 b is provided on the downstream side in the transport direction of the cyan ink head C. In addition, the pre-curing irradiation unit 42c is provided on the downstream side in the transport direction of the magenta ink head M, and the pre-curing irradiation unit 42d is provided on the downstream side in the transport direction of the yellow ink head Y.

  The length in the medium width direction of these pre-curing irradiation units 42a to 42d is equal to or greater than the medium width, and the dots formed on the medium by each head can be irradiated with UV light for pre-curing. In the present embodiment, temporary curing is a process of irradiating UV in order to suppress bleeding between inks and the spread of dots. The provisional curing irradiation units 42a to 42d of the present embodiment include light emitting diodes (LEDs) as light sources for UV irradiation. The LED can easily change the irradiation intensity by controlling the magnitude of the input current.

  The main curing irradiation unit 44 irradiates UV for main curing the dots formed on the medium by each head, and among the temporary curing irradiation units 42a to 42d, the temporary curing for the most downstream side in the transport direction. It is disposed downstream of the irradiation unit 42d in the transport direction.

The main curing irradiation unit 44 of the present embodiment includes a lamp (metal halide lamp, mercury lamp, etc.) as a UV irradiation light source, and the length of the main curing irradiation unit 44 in the medium width direction is equal to or greater than the medium width. is there. Then, the main curing irradiation unit 44 irradiates UV for main curing toward the printing surface of the paper S on which dots are formed and temporarily cured. In the present embodiment, the main curing is a process of irradiating UV in order to completely cure the dots.
The details of temporary curing and main curing will be described later.

  The detector group 50 includes a rotary encoder (not shown), a paper detection sensor (not shown), and the like. The rotary encoder detects the rotation amount of the upstream side conveyance roller 21A and the downstream side conveyance roller 21B. The transport amount of the medium can be detected based on the detection result of the rotary encoder.

  The controller 60 is a control unit (control unit) for controlling the printer 1. The controller 60 includes an interface unit 61, a CPU 62, a memory 63, and a unit control circuit 64. The interface unit 61 transmits and receives data between the computer 110 that is an external device and the printer 1. The CPU 62 is an arithmetic processing unit for controlling the entire printer. The memory 63 is for securing an area for storing a program of the CPU 62, a work area, and the like, and includes storage elements such as a RAM and an EEPROM. The memory 63 has a register for holding control information such as a flag to be described later. The CPU 62 controls each unit via the unit control circuit 64 in accordance with a program stored in the memory 63.

<About the configuration of the head>
As described above, the printer 1 of the present embodiment includes four color ink heads (black ink head K, cyan ink head C, magenta ink head M, and yellow ink head Y). Each of these heads discharges UV ink (color ink) for printing an image for each ink color.
FIG. 3 is an explanatory diagram of an example of the nozzle arrangement of each head. In this embodiment, the black ink head K, the cyan ink head C, the magenta ink head M, and the yellow ink head Y all have the same configuration. In the figure, one of the four heads is shown.

As shown in the figure, the nozzles of the head are arranged at an interval (nozzle pitch) of 600 dpi (1/600 inch) along the nozzle row direction (paper width direction). The nozzle row direction corresponds to a predetermined direction, and is a direction that intersects the transport direction (corresponding to the intersecting direction) of the paper S. Thereby, color dots can be formed at a resolution of 600 dpi in the paper width direction. Further, the resolution in the transport direction can be adjusted by the ejection timing of ink from the nozzles and the transport speed. In the present embodiment, dots are formed with a resolution of 600 dpi in the transport direction (printing resolution is 600 × 600 dpi).
A piezo element is provided corresponding to each nozzle. Then, based on applying the drive signal to the piezo element, ink is ejected from the nozzle corresponding to the piezo element.

<About temporary curing and main curing>
The printer 1 according to the present embodiment includes provisional curing irradiation units 42a to 42d and a main curing irradiation unit 44 as the irradiation unit 40, and performs two-stage curing, that is, temporary curing and main curing after the dots are formed. ing. Hereinafter, the function of each curing will be described.

Temporary curing is UV irradiation performed to suppress bleeding between inks and spreading of dots by curing the surface of the dots. The amount of UV irradiation applied to the dots during this temporary curing is small, and the UV ink (dots) is not completely cured even after the temporary curing. The irradiation amount (mJ / cm ² ) is the product of irradiation intensity (mW / cm ² ) and irradiation time (sec). In this embodiment, since the medium conveyance speed is constant (irradiation time by each irradiation unit is constant), the irradiation amount depends on the irradiation intensity.

4A to 4C are explanatory diagrams of the relationship between the timing of UV irradiation in temporary curing and the shape of UV ink (dots). Note that the UV irradiation timing is delayed in the order of FIGS. 4A, 4B, and 4C.
When the UV irradiation timing is early, for example, as shown in FIG. 4A. In this case, it is possible to suppress bleeding between inks and spread of dots, but the gloss becomes worse because the unevenness of the medium surface constituted by the dots becomes large.
On the other hand, when the UV irradiation timing is late, for example, as shown in FIG. 4C. In this case, the gloss is good. However, bleeding tends to occur between other inks.

  The main curing is UV irradiation performed to completely cure the ink. The UV irradiation amount in the main curing is larger than the UV irradiation amount in the temporary curing.

  As described above, in this embodiment, since temporary curing is performed immediately after the dots are formed by each head, it is possible to suppress bleeding between inks and the spread of dots, and to prevent deterioration in image quality regardless of the timing of performing the main curing. Can do. Therefore, you may make it provide the irradiation part 44 for main hardening in the downstream of a conveyance direction rather than the position shown in FIG.

<About print processing>
When the printer 1 starts printing, the paper S is supported by the upstream-side transport roller 21 </ b> A and the downstream-side transport roller 21 </ b> B in a state in which the paper S is laid along the peripheral surface of the transport drum 22 in advance.

  When the printer 1 receives print data from the computer 110, the controller 60 rotates a transport motor (not shown) at a constant speed. Thereby, the upstream side conveyance roller 21A and the downstream side conveyance roller 21B rotate at a constant speed in the arrow direction of FIG. In addition, this rotation causes the transport drum 22 to rotate in the direction of the arrow (transport direction). The paper S along the peripheral surface of the transport drum 22 and supported by the upstream transport roller 21 </ b> A and the downstream transport roller 21 </ b> B is transported in the transport direction according to the rotation of the transport drum 22. Note that the paper S being transported is electrostatically attracted or vacuum attracted to the transport drum 22. In the present embodiment, since the position of each head is fixed, by transporting the paper S in the transport direction, each head and the paper S move relatively in the transport direction (cross direction).

  The controller 60 intermittently ejects ink from the nozzles of each head of the head unit 30 based on the image data received from the computer 110 while the paper S is being transported on the peripheral surface of the transport drum 22 (dots). Forming operation). In this way, dots are formed on the medium and UV is irradiated from each irradiation unit of the irradiation unit 40.

FIG. 5 is a flowchart of print processing by the printer 1 of the present embodiment.
First, when the paper S passes under the black ink head K, black ink is ejected from the black ink head K to print black (S101). Then, after printing black, UV is irradiated from the pre-curing irradiation unit 42a to perform pre-curing of dots formed with black ink (S102).

  Next, when the paper S passes under the cyan ink head C, the controller 60 discharges cyan ink from the cyan ink head C to print cyan (S103). Then, after the printing, UV is irradiated from the pre-curing irradiation section 42b to perform pre-curing of the dots formed with the cyan ink (S104).

  Similarly, the controller 60 ejects magenta ink from the magenta ink head M to print magenta (S105), and irradiates UV from the pre-curing irradiation unit 42c to temporarily cure the dots formed with magenta ink. (S106). Further, yellow ink is ejected from the yellow ink head Y to print yellow (S107), and UV is irradiated from the pre-curing portion irradiation unit 42d to temporarily cure the dots formed with the yellow ink (S108).

  Finally, the controller 60 performs main curing of each dot on the paper S by irradiating UV from the main curing irradiation unit 44 (S109). Thereby, each dot formed on the paper S is completely cured.

  As described above, in the printer 1 according to the present embodiment, since each head (nozzle row) is provided along the paper width direction, dots corresponding to the width of the paper S can be formed at a time.

<About head misalignment>
In the printer 1 of the present embodiment, four heads are provided for each ink color as described above. However, these heads are not necessarily attached at accurate positions. For example, there may be a positional deviation between the heads due to an error in the head mounting position when the printer 1 is manufactured, or the head (nozzle row) may be mounted inclined with respect to the paper width direction.

  6 is an explanatory diagram when the mounting position of the head is normal, and FIG. 7 is an explanatory diagram when the head is mounted tilted (obliquely) with respect to the paper width direction. In FIG. 7, the width of the paper S is shorter than the length of the nozzle row. These drawings show one of the four heads, and the number of nozzles in the nozzle row is six for the sake of simplicity.

  In the figure, the left figure shows image data. In the image data, the X direction corresponds to the medium transport direction, and the Y direction corresponds to the paper width direction. In the image data in the figure, white circles indicate data that does not eject ink (does not form dots), and black circles indicate data that ejects ink (forms dots). As shown in the figure, the image data is data for 3 pixels in the X direction and 6 pixels in the Y direction. The image data is converted to the print resolution (600 dpi × 600 dpi) of the printer 1 by the printer driver of the computer 110.

  Based on such image data, the controller 60 ejects ink from each nozzle of the head while transporting the paper S in the transport direction. The figure on the right side shows an image (dot) printed on the paper S. In FIG. 6, ink is ejected from the six nozzles of the head at the same timing based on the image data, and six dots (black circles) are formed on the paper S side by side in the paper width direction.

  However, when the head is mounted obliquely as shown in FIG. 7, even if ink is ejected from each nozzle at the same timing, the printing result is also inclined as shown on the right side (shift of dot formation position). Occurs). In FIG. 7, the ink ejected from the farthest and frontmost nozzles in the paper width direction is detached from the paper S and landed. In this case, since ink adheres to the peripheral surface of the transport drum 22, when the transport drum 22 transports the paper S thereafter, the paper S may be stained with ink.

  Therefore, in this embodiment, a clipping flag is provided for each nozzle so as to prevent ink from landing on paper other than the paper S. Clipping is a technique for erasing a portion outside a specific area (that is, not forming dots) when forming an image.

  FIG. 8 is an explanatory diagram of a dot forming operation in the present embodiment. Also in this embodiment, the head is attached to be inclined with respect to the paper width direction as in FIG. However, in this embodiment, a clipping flag is provided for each nozzle. In this flag, either ejection valid (▲) or ejection invalid (Δ) is set for each nozzle. For example, the innermost nozzle and the foremost nozzle in the paper width direction are disabled to discharge, and the other nozzles are enabled to discharge. The controller 60 refers to the flag at the time of image formation and does not forcibly eject ink from the nozzle whose flag is invalid (Δ) regardless of the image data (that is, prohibits ink ejection). ), Ink is ejected based on the image data only from nozzles whose flag is valid (▲).

  When executing printing, the controller 60 does not force ink to be ejected from nozzles whose ejection is disabled (the farthest side and the foremost side in the paper width direction). Specifically, for example, a switch is provided for each signal line that supplies a drive signal to the piezo element, and when the flag is invalid (Δ), the corresponding switch corresponding to the nozzle (piezo element) is turned off. To. By doing so, the drive signal is not applied to the piezo element, so that it is possible not to forcibly eject ink regardless of the image data.

  In this example, ink is not ejected from the farthest and frontmost nozzles in the paper width direction, and ink is ejected from four nozzles therebetween. Therefore, as shown in the drawing on the right side, ink is landed only on the paper S, and ink landing on a place other than the paper S can be prevented.

<How to set the flag>
FIG. 9 is a flowchart showing an example of a flag setting method. In this example, a flag is set by printing a test pattern in advance before printing. Although the printer 1 of this embodiment includes four heads, the same processing is performed on each head, and a flag is set for each head (that is, for each nozzle row).

  First, the controller 60 prints a test pattern by ejecting ink from the nozzle row of each head while transporting the paper S in the transport direction (S201). The test pattern printed in this way is read by a reading device such as a scanner (S202). Then, an ink ejection valid (▲) or ejection invalid (Δ) flag is set for each nozzle from the test pattern reading result (S203). The flag is held in the register of the memory 63 for each nozzle.

  When printing on the paper S, the controller 60 executes printing with reference to the flags set for the respective nozzles as described above. That is, if the flag is invalid (Δ), ink is ejected from the nozzle based on the image data, and if the flag is Δ, the ink is not forcibly ejected regardless of the image data.

  By doing so, ink can be reliably ejected onto the paper S regardless of the mounting accuracy of the individual heads (nozzle rows) of the apparatus. Accordingly, it is possible to prevent ink from landing on other than the paper S.

<Modification>
In the above-described embodiment, since the head is attached to be inclined with respect to the paper width direction, the print result also has an inclination corresponding to the inclination of the head (shift of the dot formation position). In this modification, control information for controlling the ink ejection timing is provided for each nozzle in addition to the ejection valid / invalid flag (a total of 2 bits of control information is provided). Thereby, the shift of the dot formation position is reduced.

  FIG. 10 is an explanatory diagram of a dot forming operation in the modification. In this modification, the resolution in the transport direction is changed from the above-described embodiment. Specifically, the resolution (1200 dpi) is double the resolution (600 dpi) of the above-described embodiment in the transport direction, and the discharge timing for each nozzle is divided into two stages, a first timing and a second timing. Note that the second timing is, for example, a timing later than the first timing by half of the ejection cycle. In this modification, 2-bit control information is provided for each nozzle, the discharge timing is set by the first bit, and the discharge valid / invalid flag is set by the second bit. For example, a nozzle indicated by a white square (□) in the figure is a nozzle that ejects ink at a first timing, and a nozzle indicated by a black square (■) is a nozzle that ejects ink at a second timing. As a result, even if the image data causes ink to be ejected from each nozzle of the head at the same timing, the ink is ejected from the nozzle (□ nozzle) set at the first timing first, and then set to the second timing. Ink is ejected from the nozzles (■ nozzles).

  Also in this example, as in the above-described embodiment, the flags corresponding to the farthest and foremost nozzles in the paper width direction are disabled (Δ). In this way, control information (first bit) indicating the ink ejection timing and 2-bit control information of the ink ejection valid / invalid flag (second bit) are set for each nozzle. . The 2-bit control information is held in a register of the memory 63.

  As a result, when an image is formed based on the image data of the figure, it becomes as shown on the right side of FIG. 10, and variation in dot formation position (variation in ink landing position in the transport direction) compared to the case of FIG. Has been reduced.

  In this modification as well, as in the above-described embodiment, the control information of the flag and the ejection timing may be set in advance for each nozzle in accordance with the test pattern printed and the reading result. For example, in the present embodiment, the ejection timing is changed between the three nozzles on the back side in the paper width direction and the three nozzles on the front side among the six nozzles in the nozzle row in the figure, but this is not a limitation. For example, the ejection timing may be changed between two nozzles on the back side in the paper width direction and four nozzles on the front side based on the print result of the test pattern.

  According to this modification, as shown on the right side of the drawing, it is possible to reduce the deviation of the dot formation position due to the tilting of the head, and it is possible to suppress the deterioration of the image quality. Further, since ink is not ejected from the nozzle whose flag is invalid (Δ), it is possible to prevent ink from landing on other than the paper S.

=== Second Embodiment ===
In the above-described embodiment, a flag is set before printing an image to be printed on the paper S by printing a test pattern in advance. In the second embodiment, however, the flag is set according to the transport state of the paper S. Set flags as needed. Note that the printer 1 of the second embodiment includes a paper detection sensor (not shown) that detects the paper S being conveyed as the detector group 50. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  A paper detection sensor (corresponding to a detection sensor) is provided corresponding to each head of the head unit 30, and is disposed at least upstream in the transport direction (that is, the transport path) from the nozzle row of each head. ing. The paper detection sensor detects the state of the paper S being conveyed (paper width, presence / absence of meandering, etc.).

FIG. 11 is a flowchart showing the flag setting method of the second embodiment.
During printing (during the dot formation operation), the paper detection sensor detects the paper width of the paper S being conveyed in the conveyance direction, the presence / absence of meandering, etc. at predetermined sampling periods (S301). Based on the detection result, the paper detection sensor determines the transport state of the paper S, and sets a flag for each nozzle of the corresponding head (nozzle row) (S302). When ejecting ink from the nozzles of the head, the controller 60 refers to the flag provided for each nozzle and executes printing using the flag as in the first embodiment.

  As described above, in the second embodiment, a paper detection sensor (not shown) detects the transported paper S, and sets a flag corresponding to each nozzle as needed from the reading result. Thereby, for example, even when the paper S is transported obliquely with respect to the transport direction, it is possible to perform control for preventing ink landing on other than the paper S at high speed. In the case of the second embodiment, for example, it is possible to cope with a case where the user makes a mistake in the size of the paper S set in the printer 1.

=== Third Embodiment ===
In the third embodiment, a plurality of identical images T (labels, etc.) are formed side by side in the transport direction and the paper width direction of the paper S. Similar to the second embodiment, the printer 1 of the third embodiment includes a paper detection sensor (not shown) on the upstream side in the transport direction from each head, and the paper detection sensor performs a dot forming operation. In addition, the paper S (paper width, presence / absence of meandering, etc.) is detected. Also in the third embodiment, a flag indicating ejection validity / invalidity is set for each nozzle, and the flag is rewritten as needed according to the detection result of the paper detection sensor as in the second embodiment. Since other printer configurations and image forming operations are the same as those in the above-described embodiment, description thereof will be omitted. The printer 1 according to the present embodiment is provided with four heads (black ink head K, cyan ink head C, magenta ink head M, and yellow ink head Y) as shown in FIG. For the sake of simplicity, an image is formed with one of the heads (one color).

  FIG. 12 is a diagram illustrating an example of an image formed in the third embodiment. The image data is data formed by arranging four images T in the paper width direction. Based on this image data, by ejecting ink from the head onto the paper S being transported in the transport direction, four images T arranged in the paper width direction are repeatedly printed in the transport direction.

  However, a part of the lowermost image T of the paper S in FIG. For this reason, the ejection detection flag (see FIG. 8) is set by the paper detection sensor to the nozzles corresponding to the portions of the nozzles of the head that are out of the paper S, as in the previous embodiment. In the third embodiment, when the nozzle that forms the image T has a discharge invalid flag in this manner, the controller 60 does not depend on the image data, but the entire image T corresponding to the nozzle for which the discharge invalid flag is set. (Images indicated by dotted lines in FIG. 12) are not formed.

  If dots are not formed only on the nozzles with the ejection invalid flag, a plurality of incomplete images T are formed on the paper S, and there is a possibility that ink is wasted. On the other hand, in the third embodiment, an incomplete image T (that is, an image T partially removed from the paper S) is formed by not forming the image T with the flag based on the discharge invalid flag. Can be prevented. Thereby, the consumption of ink can be reduced. Further, since the formation of an incomplete image T can be prevented, it is very easy to determine whether the image is a non-defective product or a defective product in a process after the image formation.

  In this embodiment, an image is formed with one head (one color). However, when an image is formed with four heads (four colors), each head is based on the detection result of the paper detection sensor. It is only necessary to prevent the image from deviating from the paper S.

=== Fourth Embodiment ===
In the above-described embodiment, the head is fixed on the transport path, and ink is ejected from the nozzles of the head while transporting the paper S in the transport direction. However, in the fourth embodiment, the head is disposed in the nozzle row direction. Ink is ejected from the head while moving in the intersecting direction to form an image.

  FIG. 13 is a block diagram of the overall configuration of the printer 1 according to the fourth embodiment. FIG. 14A is a schematic sectional view of the printer 1 of the fourth embodiment, and FIG. 14B is a schematic top view of the printer 1 of the fourth embodiment.

  The printer 1 that has received print data from the computer 110, which is an external device, controls the units (conveyance unit 20, drive unit 70, head unit 30) by the controller 60, and the paper S (continuous paper) located in the print area. An image is formed on. Further, the detector group 50 monitors the situation in the printer 1, and the controller 60 controls each unit based on the detection result.

  The transport unit 20 transports the paper S from the upstream side to the downstream side in the transport direction (corresponding to the crossing direction), and includes a transport roller 23 driven by a transport motor (not shown). The transport unit 20 supplies the roll-shaped paper S before printing to the printing area by the transport roller 23, and then winds the printed paper S into a roll by a winding mechanism. In the printing area during printing, the paper S is vacuum-sucked from below, and the paper S is held at a predetermined position.

  The drive unit 70 freely moves the head unit 30 in the transport direction and the paper width direction (corresponding to a predetermined direction). The drive unit 70 includes a stage 71 that moves the head unit 30 in the transport direction, a stage 72 that moves the stage 71 in the paper width direction, and a motor (not shown) that moves them.

The head unit 30 is for forming an image and has a plurality of heads 31. A plurality of nozzles for ejecting ink are provided on the lower surface of the head 31, and an ink chamber containing ink is provided for each nozzle.
Note that the paper S being printed is supported by a platen (not shown) (corresponding to a support portion).

  Next, a printing procedure will be described. First, the controller 60 moves the head unit 30 in the transport direction by the stage 71 with respect to the paper S supplied to the printing area by the transport unit 20. That is, the head unit 30 and the paper S are moved relatively in the transport direction. During this movement, the controller 60 causes ink to be ejected from the nozzles of the head unit 30 to form dot rows along the transport direction on the paper S (dot forming operation). Thereafter, the controller 60 causes the stage 72 to move the head unit 30 in the paper width direction via the stage 71. Then, again, the controller 60 performs printing while moving the head unit 30 in the transport direction. As described above, the dot formation operation by the movement of the head unit 30 in the transport direction and the movement of the head unit 30 in the paper width direction are alternately repeated, so that the positions of the dots formed by the previous dot formation operation are different. A dot can be formed at the position, and the image is completed. In this way, when the printing of the paper S supplied to the printing area is completed, the portion of the paper S that has not yet been printed by the transport unit 20 is supplied to the printing area (conveying operation), and again the paper S in the printing area. An image is formed. In the printer 1 of the present embodiment, such an image forming operation (a plurality of dot forming operations) to the print region and the paper S transport operation are alternately repeated.

<About the arrangement of the head 31>
FIG. 15 is a diagram illustrating an arrangement of a plurality of heads 31 in the head unit 30 of the fourth embodiment. In practice, the nozzle surface is formed on the lower surface of the head unit 30, but FIG. 15 is a view of the nozzle virtually viewed from the upper surface (the same applies to the following drawings). By arranging a large number of nozzles in the paper width direction, an image having a large width can be printed by one movement of the head unit 30 in the transport direction. By doing so, the printing speed can be increased. However, a long head cannot be formed due to manufacturing problems. Therefore, in the printer 1, a plurality of short heads 31 (n) are arranged side by side in the paper width direction. As shown in the drawing, the plurality of heads 31 are attached to the base plate BP. In the manufacturing process of the printer 1, the base plate BP to which the plurality of heads 31 are attached is attached to the main body of the printer 1.

  On the nozzle surface of each head 31, a yellow nozzle row Y for discharging yellow ink, a magenta nozzle row M for discharging magenta ink, a cyan nozzle row C for discharging cyan ink, and a black nozzle row for discharging black ink. K is formed. Each nozzle row includes 180 nozzles, and the 180 nozzles are aligned at a constant interval (600 dpi) in the paper width direction. As shown in the figure, numbers are assigned in order from the nozzles on the back side in the paper width direction (# 1 to # 180).

  Of the two heads adjacent to each other in the paper width direction (for example, 31 (1) and 31 (2)), the nozzle # 180 on the front side of the head 31 (1) on the back side and the head 31 (2 on the front side) ) With the innermost nozzle # 1 is also a constant interval (600 dpi). That is, on the lower surface of the head unit 30, the nozzles are arranged at a constant interval (600 dpi) in the paper width direction. Note that end nozzles of different heads 31 may overlap.

  As shown in FIG. 15, in order to set the distance between the end nozzles of different heads 31 to 600 dpi, it is necessary to arrange the heads 31 in a staggered manner due to structural problems of the heads 31. When a plurality of heads 31 are arranged in a staggered manner in this way, in order to form a straight line along the paper width direction, the liquid from the head 31 (odd-numbered head, for example, 31 (1)) on the downstream side in the transport direction. It is necessary to correct the timing at which the liquid is discharged and the timing at which the liquid is discharged from the upstream head 31 (even numbered head, for example, 31 (2)) in the transport direction. Hereinafter, a method for correcting the ejection timing (dot formation position) from the head 31 whose position in the transport direction is shifted will be described.

<Regarding dot formation in the comparative example>
FIG. 16 is a diagram for explaining a dot formation position correction method according to a comparative example. Hereinafter, for simplicity of explanation, the number of heads 31 included in the head unit 30 is four. The shift amount in the transport direction in the design of the heads 31 (1) and (3) on the downstream side in the transport direction and the heads 31 (2) and (4) on the upstream side in the transport direction is known in advance. Here, as illustrated, the difference between the attachment position of the downstream head 31 in the conveyance direction and the attachment position of the upstream head 31 in the conveyance direction is referred to as “deviation amount ΔX”.

  For example, when the head unit 30 moves from the downstream side in the transport direction to the upstream side, when the ink is discharged from the upstream head 31 and the downstream head 31 to the same position in the transport direction on the medium S, the upstream head 31 (2) (4) faces the target discharge position earlier than the downstream heads 31 (1) (3). Then, after the upstream heads 31 (2) and (4) face the target position, the head unit 30 moves by “deviation amount ΔX” in the transport direction, and then the downstream heads 31 (1) and (3) Opposite the position.

  Therefore, in terms of design, the downstream head 31 (1) is discharged after the time required for the head unit 30 to move by ΔX in the transport direction after the liquid is discharged from the upstream heads 31 (2) (4). The liquid is discharged from (3). By doing so, it is possible to align the dot formation positions in the transport direction in the upstream heads 31 (2) and (4) and the dot formation positions in the transport direction in the downstream heads 31 (1) and (3). Then, a straight line along the paper width direction can be formed by the plurality of heads 31 arranged in a zigzag shape included in the head unit 30.

  However, in reality, dots may be formed with a deviation from the target position at the designed ejection timing due to an attachment error that occurs when the head 31 is attached to the base plate BP, a difference in ejection characteristics of each head 31, or the like. is there. Therefore, in the manufacturing process of the printer 1 and the like, each printer 1 is actually printed with a test pattern, and a dot formation position correction value in the transport direction of each head 31 is calculated based on the test pattern.

  Hereinafter, a method for obtaining a correction value of the dot formation position in the comparative example will be described. FIG. 16 shows a test pattern formed on the medium S located in the printing area. In order to form such a test pattern, first, a target position is set on the medium S. Then, the ink is ejected from each head 31 at the designed ejection timing so that the ink ejected from the respective heads 31 arranged in a staggered pattern reaches the target position. Here, as a test pattern, ink is ejected from all 180 nozzles of each head 31. However, the present invention is not limited to this. For example, ink may be ejected from every other nozzle. As a result, as shown in FIG. 16, each head 31 (1) to 31 (4) forms a dot row along the paper width direction (nozzle row direction).

  When the test pattern is specifically seen, the line formed by the first head 31 (1) is formed without deviating from the target position. From this, it is understood that the ejection timing of the first head 31 does not need to be corrected from the designed ejection timing.

  On the other hand, the line formed by the second head 31 (2) and the fourth head 31 (4) is formed to be shifted to the upstream side in the transport direction from the target position and beyond the target position. From this, it can be seen that the second head 31 (2) and the fourth head 31 (4) need to eject ink at a timing earlier than the designed ejection timing.

  On the contrary, the line formed by the third head 31 (3) is shifted to the downstream side in the transport direction from the target position, and is formed in front of the target position. From this, it can be seen that the third head 31 (3) needs to eject ink at a timing later than the designed ejection timing.

  Then, from the test pattern result, it is possible to know how much the ejection timing should be corrected by acquiring the deviation amount between the target position and the actually formed line. For example, the line of the fourth head 31 (4) in FIG. 16 is formed so as to be shifted to the upstream side in the transport direction by “ΔY” from the target position. For this reason, it is preferable that the ejection timing of the fourth head 31 (4) be advanced from the designed ejection timing by the time during which the head unit 30 moves the “deviation amount ΔY”. By doing so, the line by the 4th head 31 (4) can be formed in a target position. In order to obtain the deviation amount ΔY, the printed test pattern may be read by the scanner, and the difference between the target position and the line position on the read data may be calculated. Alternatively, the target position and line may be calculated from the test pattern. You may measure the difference with this position.

  In this comparative example, when the amount of deviation ΔY between the target position and the position of the line formed by each head 31 is acquired, the center portion of the line formed by each head 31 is used as a reference. That is, the ejection timing of the head 31 is determined by the amount of deviation ΔY in the transport direction between the line portion (the portion circled in FIG. 16) formed by the central portion of the nozzle row (for example, nozzle # 90) and the target position. adjust. Thus, the dot formation position of each head 31 can be corrected according to the ejection characteristics and attachment errors. When an image is formed when the head unit 30 moves in both directions in the transport direction (when performing bidirectional printing), the head unit 30 moves from the downstream side in the transport direction to the upstream side as shown in FIG. It is preferable to form a test pattern by the head unit 30 and a test pattern by the head unit 30 moving from the upstream side to the downstream side in the transport direction.

  FIG. 17 is a diagram illustrating a state in which the head unit 30 of the fourth embodiment is tilted during movement in the transport direction. As shown in FIGS. 14B and 15, in the printer 1 of the present embodiment, the head unit 30 is moved in the transport direction only by the stage 71 (the drive shaft to which the drive motor is attached) on the back side in the paper width direction. That is, only one end of the head unit 30 in the paper width direction is driven. In addition, since many heads 31 are arranged in the transport direction in the head unit 30, the head unit 30 is relatively heavy and has a structure that is long in the paper width direction.

  Therefore, when the head unit 30 is moved in the transport direction, a strong inertial force acts on the end of the head unit opposite to the stage 71 (on the front side in the paper width direction), and as shown in FIG. Tends to tilt. Specifically, when the head unit 30 moves from the downstream side to the upstream side in the transport direction, the head unit 30 tilts clockwise, and when the head unit 30 moves from the upstream side to the downstream side in the transport direction, it rotates counterclockwise. Tilt in the direction. That is, when the direction in which the head unit 30 moves is different, the direction in which the head unit 30 is tilted is also different. In FIG. 17, the head unit 30 is drawn with a large inclination for the sake of explanation, but the actual inclination is very small.

  The phenomenon that the head unit 30 is inclined with respect to the paper width direction during the movement of the head unit 30 in the transport direction is likely to occur when only one side of the head unit 30 is driven. In particular, when no guide rail or the like is provided on the opposite side of the stage 71 (drive shaft) as in the printer 1 of the present embodiment, the head unit 30 is more easily tilted.

  FIG. 18A is a diagram showing a test pattern formed by the head unit 30 that is tilted during movement in the transport direction, and FIG. 18B shows a line corrected by the correction method of the comparative example based on the test pattern result of FIG. 18A. FIG. FIG. 18 shows a test pattern formed when the head unit 30 moves from the downstream side to the upstream side in the transport direction (hereinafter also referred to as the forward path). As shown in FIG. 17, since the head unit 30 tends to tilt clockwise in the forward path, the line formed as the test pattern is also tilted clockwise with respect to the paper width direction. In addition, the head unit 30 is not limited to be tilted, but the individual heads 31 may be tilted due to attachment errors or the like. In that case, the inclination of the line formed by each head 31 also differs.

  In the dot forming position correction method in the comparative example, the amount of deviation in the transport direction (deviation from the target position) is based on the center of the line formed in each head 31 as a test pattern (the part circled in the figure). Amount) is corrected. For example, the central portion of the line formed in the second head 31 (2) is located on the upstream side in the transport direction. Therefore, as a result of correcting the ejection timing so that the center of the line of the second head 31 (2) is positioned at the target position, the entire line of the second head 31 (2) is downstream in the transport direction as shown in FIG. 18B. It is formed shifted to the side. Therefore, according to the correction method of the comparative example, as shown in FIG. 18B, the central portion of the line formed by each head 31 is positioned on a straight line at the target position.

  However, the line formed by the head 31 inclined with respect to the paper width direction differs in position in the transport direction depending on the location of the line, and the amount of deviation from the target position also differs. For example, in FIG. 18B, the center portion of the line by the first head 31 (1) is located at the target position, but the upper end portion (back end portion) of the line is located upstream in the transport direction from the target position. The lower end (front end) of the line is located downstream of the target position in the transport direction.

  For this reason, when the lines formed side by side in the paper width direction are inclined in the same direction, the joint portion of the lines is greatly displaced in the transport direction. For example, the end of the line of the first head 31 (1) on the second head 31 (2) side is located downstream of the target position in the transport direction, whereas the line of the second head 31 (2) The end of the first head 31 (1) side is located upstream of the target position in the transport direction. The fact that the joints of the lines of the different heads 31 are shifted in the transport direction in this way means that an image formed on each head 31 is shifted in the transport direction, and the image quality is deteriorated.

  As shown in FIG. 17, when the head unit 30 is moving, the entire head unit 30 (base plate BP) is tilted, or the heads 31 arranged side by side in the paper width direction are tilted and attached in the same direction. In addition, lines formed side by side in the paper width direction are inclined in the same direction. Then, in the dot formation position correction method of the comparative example, the image of the joint portion of the head 31 is particularly deteriorated. As described above, since the printer 1 according to the present embodiment moves the head unit 30 in the transport direction particularly by driving only one side, the head provided on the head unit 30 (base plate BP) as shown in FIG. When 31 forms dots, it tends to tilt in the same direction.

  Therefore, in the fourth embodiment, such a shift in the conveyance direction of the dot formation position at the joint portion is suppressed, and image deterioration is suppressed.

<About Dot Formation in the Fourth Embodiment>
In the fourth embodiment, 2-bit control information similar to that of the modification of the first embodiment is set for each head of the head unit 30. Then, after performing the correction process as shown in FIG. 18B of the comparative example, the ejection timing (first bit) is set for each nozzle of the head. Note that the second bit indicating ejection validity / invalidity is also set in the same manner as in the above-described embodiment. In this way, by setting 2-bit control information for each head, it is possible to reduce variations in dot formation positions, as in the modification of the first embodiment, and to shift the joint portion of the head. Can be reduced.

  FIG. 19 is a diagram showing a test pattern formed according to the fourth embodiment. In the state corrected as shown in FIG. 18B, the test timing as shown in FIG. 19 can be formed by setting the ejection timing for the nozzles of each head as in the modification of the first embodiment. Compared with FIG. 18B, the shift of the end of the line is less noticeable.

  Further, FIG. 19 shows only the test pattern formed in the forward path, but the test pattern may be formed in the same way for the return path. In the return path, as shown in FIG. 17, the inclination of the head unit 30 is opposite to that of the forward path, so the inclination of the line of the test pattern is also opposite to that in FIG. In this case as well, the discharge timing may be adjusted as in the forward path. Then, 2-bit control information may be switched between the forward path and the return path.

  By so doing, it is possible to reduce variations in dot formation positions due to the inclination of the head unit 30 in the forward path and the backward path.

  In the fourth embodiment, the inclination direction of the head unit 30 is reversed in the forward path and the backward path. However, the direction is not limited to this, and the head unit 30 may be inclined in the same direction in the forward path and the backward path. In this case as well, it is only necessary to print the test pattern for each of the forward path and the backward path, and set the ejection timing of each head (nozzle row) based on the test pattern printing result. In the forward path and the backward path, there is a possibility that the nozzles that eject ink to different locations from the paper S are different. Therefore, it is desirable to set a flag as in the above-described embodiment for the forward path and the backward path for each nozzle. By doing so, it is possible to prevent ink landing on other than the paper S (for example, the platen) in each of the forward path and the return path.

=== Other Embodiments ===
Although a printer or the like as one embodiment has been described, the above embodiment is for facilitating the understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About the printer>
In the above-described embodiment, a line type printer or a lateral type printer has been described as an example of the apparatus. However, the present invention is not limited to this. For example, a serial type printer that alternately repeats a dot forming operation for ejecting ink while moving a nozzle row in which nozzles are arranged in the transport direction in a moving direction intersecting the transport direction and a transport operation for transporting paper in the transport direction. Good.

<Discharge method>
In the embodiment described above, ink is ejected by applying a voltage to the piezoelectric element (piezo element) (piezo method). However, the method for discharging the liquid is not limited to this. For example, another method may be used such as a thermal method in which bubbles are generated in the nozzle using a heating element and ink is ejected by the bubbles.

1 Printer 20 Conveying Unit 21A Upstream Conveying Roller 21B Downstream Conveying Roller 22 Conveying Drum 23 Conveying Roller 30 Head Unit 31 Head 40 Irradiation Units 42a to 42d Preliminary Curing Irradiation Unit 44 Main Curing Irradiation Unit 50 Detector Group 60 Controller 61 Interface unit 62 CPU
63 Memory 64 Unit control circuit 70 Drive unit 71 Stage (conveyance direction)
72 stages (paper width direction)
110 computer

Claims (7)

A nozzle row in which a plurality of nozzles for discharging liquid are arranged in a predetermined direction;
A clipping flag in which either ejection valid or ejection invalid is set for each nozzle of the nozzle row, and
Control for forming an image on the medium by performing a dot forming operation of ejecting the liquid from each nozzle while moving the nozzle array and the medium in a crossing direction intersecting the predetermined direction based on image data A controller that prohibits the discharge of the liquid from the nozzles whose discharge is disabled during the dot forming operation regardless of the image data;
An image forming apparatus comprising: The image forming apparatus according to claim 1,
Forming a test pattern on the medium before forming the image;
An image forming apparatus, wherein the flag is set for each nozzle based on a reading result of the test pattern. The image forming apparatus according to claim 1, wherein:
A support unit that supports the medium and faces the nozzle row via the medium;
A detection sensor that is provided on the upstream side of the conveyance path of the medium from the nozzle row and detects the medium;
An image forming apparatus comprising: disabling ejection of the flag corresponding to a nozzle that ejects the liquid to the support portion based on a detection result of the detection sensor. The image forming apparatus according to claim 1,
Control information different from the flag, and control information for controlling the discharge timing of the liquid is provided for each nozzle.
An image forming apparatus. The image forming apparatus according to claim 4,
The control unit reciprocates the nozzle row in one direction side and the other direction side in the intersecting direction during the dot forming operation,
The image forming apparatus, wherein the flag and the control information are respectively set when the nozzle row moves in the one direction and when the nozzle row moves in the other direction. An image forming apparatus according to claim 1,
The image data is formed by arranging a plurality of images in the predetermined direction of the medium using each nozzle of the nozzle row,
The control unit does not form the certain image among the plurality of images regardless of the image data when the discharge invalid flag is set in a nozzle that forms the certain image. Image forming apparatus. An image forming method for forming an image on a medium by an image forming apparatus including a nozzle row in which a plurality of nozzles for discharging liquid are arranged in a predetermined direction,
For each nozzle in the nozzle row, setting a clipping flag indicating either ejection valid or ejection invalid,
Performing a dot forming operation of ejecting the liquid from each nozzle while relatively moving the nozzle row and the medium in a crossing direction crossing the predetermined direction based on image data;
During the dot forming operation, the discharge of the liquid is prohibited regardless of the image data from a nozzle whose flag is invalid.
An image forming method comprising:

Images