JP6586821B2 - Image forming apparatus, print production method and program - Google Patents

Description

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

  2. Related Art Conventionally, an ink jet recording apparatus of a liquid discharge recording method is known. An ink jet recording apparatus is an image forming apparatus using a recording head including a liquid discharge head (droplet discharge head) for discharging droplets. As such an image forming apparatus, there is known an image forming apparatus that uses an active energy ray curable liquid such as an ultraviolet curable ink to form an image by sequentially laminating a liquid layer while laminating. An image formed by such an image forming apparatus is formed by irradiating the discharged ultraviolet curable ink (UV ink) with ultraviolet rays (UV) and curing the discharged ultraviolet curable ink. By using the active energy ray-curable liquid, a three-dimensional image can be formed and the image density can be increased.

  In addition, in order to shorten the printing time, after the stacked ink is ejected in the forward and return passes during bidirectional printing, the time for UV irradiation is made constant to improve bidirectional color unevenness and speed. The technology which balances is known. For example, Patent Document 1 discloses an invention of an ink jet printer in which a UV lamp is arranged in the center and the heads of the respective inks are arranged symmetrically with respect to the UV lamp.

  In bidirectional printing that shortens the printing time, the distance between the droplet discharge head and the UV lamp differs between the forward path and the backward path, and therefore the time required for ultraviolet irradiation differs between the forward path and the backward path. For this reason, there is a problem that unevenness in color occurs in the image due to a difference in the height of the dots of the droplets ejected from the droplet ejection head, and the quality of the image is deteriorated. Further, if the heads are arranged symmetrically as in Patent Document 1 in order to improve the color unevenness of the image due to bidirectional printing, the color unevenness of the image is improved, but the cost of the image forming apparatus is increased. There's a problem.

  The present invention has been made in view of the above, and is an image forming apparatus capable of forming a higher quality image at a lower cost and with higher productivity than in the case of unidirectional printing, and production of printed matter. An object is to provide a method and a program.

In order to solve the above-described problems and achieve the object, an image forming apparatus according to an embodiment is mounted on a recording head that moves in a main scanning direction on a recording medium, and is mounted on the recording head. A plurality of first nozzles for ejecting active energy ray-curable ink onto the recording medium when moving in the scanning direction and when the recording head moves in the main scanning direction; and the recording head A plurality of second nozzles for ejecting the active energy ray-curable ink onto the recording medium when moving in one direction of either the forward path or the backward path in the main scanning direction, A first irradiation unit disposed behind the recording head in the forward direction and irradiating the active energy ray-curable ink discharged from the droplet discharge head with active energy rays; A second irradiation unit that is disposed rearward in the road direction and irradiates the active energy ray-curable ink discharged from the droplet discharge head with active energy rays, and formed by droplets discharged from the droplet discharge head An order determining unit that divides the dot pattern data indicating the dot pattern to be divided into partial dot pattern data indicating a plurality of partial dot patterns that are a part of the dot pattern, and determines a forming order of the plurality of partial dot patterns; For each of the partial dot patterns, the formation of the partial dot pattern is assigned to the plurality of first nozzles or the plurality of second nozzles, and is finally formed at least in a unit region that is a unit of image formation. and allocation determining unit that formation of the final dot pattern indicating the partial dot pattern to be assigned to the plurality of second nozzles, An operation unit that receives an input of direction information indicating a traveling direction of the recording head when the plurality of second nozzles discharge the partial dot pattern, and the droplet discharge head includes the recording head When moving in the direction indicated by the direction information, the active energy ray-curable ink is ejected from the plurality of second nozzles onto the recording medium .

  According to the present invention, it is possible to form an image with higher image quality at a lower cost and higher productivity than in the case of unidirectional printing.

FIG. 1 is a schematic diagram illustrating an example of a cross section of the image forming apparatus according to the embodiment. FIG. 2 is a schematic diagram illustrating an example of an image forming unit of the image forming apparatus according to the embodiment. FIG. 3 is a schematic diagram illustrating an example of a conveyance unit of the image forming apparatus according to the embodiment. FIG. 4 is a diagram illustrating an example of the configuration of the control unit of the image forming apparatus according to the embodiment. FIG. 5 is a diagram illustrating an example of the configuration of the head drive control unit of the image forming apparatus according to the embodiment. FIG. 6 is a diagram showing the relationship between the dot height of ink droplets of ultraviolet curable ink and the time from ink landing to UV irradiation. FIG. 7A is a schematic diagram showing an example of a cross section of an image formed by ink droplets formed on a recording medium by conventional bidirectional printing. FIG. 7B is a schematic diagram illustrating an example of a cross section of an image formed by ink droplets formed on a recording medium by the image forming method of the embodiment. FIG. 7C is a schematic diagram illustrating an example of a cross section of an image formed by ink droplets formed on a recording medium by the image forming method according to the embodiment. FIG. 8A is a diagram showing an example of a conventional image forming method (1 pass, 1/2 interlace). FIG. 8B is a diagram showing an example of a conventional image forming method (1 pass, 1/2 interlace). FIG. 8C is a diagram illustrating an example of a conventional image forming method (1 pass, 1/2 interlace). FIG. 9A is a diagram illustrating an example of an image forming method (1 pass, 1/2 interlace) according to the embodiment. FIG. 9B is a diagram illustrating an example of an image forming method (1 pass, 1/2 interlace) according to the embodiment. FIG. 9C is a diagram illustrating an example of an image forming method (1 pass, 1/2 interlace) according to the embodiment. FIG. 9D is a diagram illustrating an example of an image forming method (1 pass, 1/2 interlace) according to the embodiment. FIG. 9E is a diagram illustrating an example of an image forming method (1 pass, 1/2 interlace) according to the embodiment. FIG. 10A is a diagram illustrating an example of a conventional image forming method (two passes). FIG. 10B is a diagram illustrating an example of a conventional image forming method (two passes). FIG. 10C is a diagram illustrating an example of a conventional image forming method (two passes). FIG. 11A is a diagram illustrating an example of an image forming method (two passes) according to the embodiment. FIG. 11B is a diagram illustrating an example of an image forming method (two passes) according to the embodiment. FIG. 11C is a diagram illustrating an example of an image forming method (two passes) according to the embodiment. FIG. 11D is a diagram illustrating an example of an image forming method (two passes) according to the embodiment. FIG. 11E is a diagram illustrating an example of an image forming method (two passes) according to the embodiment. FIG. 12 is a flowchart illustrating an example of the image forming method of the embodiment. FIG. 13 is a diagram for explaining the effect of the image forming method of the embodiment.

  Exemplary embodiments of an image forming apparatus, a printed matter production method, and a program will be described below in detail with reference to the accompanying drawings.

  First, the configuration of the image forming apparatus according to the embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic diagram illustrating an example of a cross section of an image forming apparatus 1 according to the embodiment. FIG. 2 is a schematic diagram illustrating an example of the image forming unit 2 of the image forming apparatus 1 according to the embodiment. In FIG. 2, “apparatus rear side (rear side)” corresponds to the back side of the sheet of FIG. 1, and “apparatus front side (front side)” corresponds to the front side of the sheet of FIG. 1.

  FIG. 1 illustrates an image forming unit 2, a conveyance unit 3, and a paper feeding unit 4. The recording medium 14 in the paper feed tray 105 is transported along the transport paths 310, 305, and 306 and discharged onto the paper discharge tray 104. In the conveyance path 305, the recording medium 14 is conveyed by the conveyance belt 13 and an image is formed by the image forming unit 2 including the carriage 23 and the like.

  The carriage 23 includes a recording head 24, a sub tank 25, and irradiation units (UV lamps 51 and 52).

  The recording head 24 includes a plurality of droplet discharge heads 24k, 24w, 24c, 24m, and 24y arranged in the main scanning direction. The droplet discharge head 24k discharges black (Bk) ink. The droplet discharge head 24w discharges white (W) ink. The droplet discharge head 24c discharges cyan (C) ink. The droplet discharge head 24m discharges magenta (M) ink. The droplet discharge head 24y discharges yellow (Y) ink. Each color ink is supplied from a sub tank 25 mounted on the carriage 23 for each color. The color and number of inks may be arbitrary and can be changed as necessary.

  The ink of each color in the sub tank 25 is supplied from the ink cartridge 26 (26k, 26w, 26c, 26m, and 26y). The ink cartridges 26 (26k, 26w, 26c, 26m, and 26y) contain black (Bk) ink, white (W) ink, cyan (C) ink, magenta (M) ink, and yellow (Y) ink, respectively. It is a liquid cartridge. As shown in FIG. 1, the ink cartridges 26 (26k, 26w, 26c, 26m, and 26y) are detachably mounted on, for example, a cartridge mounting portion on the front surface (front side of the paper) of the apparatus main body. The ink cartridge 26 in FIG. 1 is schematically shown, and the size ratio with the sub tank 25 is different from the actual size ratio between the sub tank 25 and the ink cartridge 26.

  The ink droplets (ink droplets) of each color are cured when irradiated with active energy rays. Examples of active energy rays include ultraviolet rays and electron beams, among which ultraviolet rays are preferable.

  Here, a configuration related to irradiation with active energy rays will be described. As shown in FIG. 2, the scanning direction of the carriage 23 is the main scanning direction, and the transport direction of the paper 5 (recording medium 14) is the sub-scanning direction. The main scanning direction is orthogonal to the sub scanning direction. Irradiation units (UV lamps 51 and 52) are arranged on both sides of the recording head 24. The UV lamp 51 is disposed behind the recording head 24 in the forward direction. The UV lamp 52 is disposed behind the recording head 24 in the backward direction.

  The UV lamps 51 and 52 irradiate the active energy ray-curable ink ejected from the recording head 24 with active energy rays. In the description of the embodiment, an ultraviolet lamp unit (UV lamp) is taken as an example of the irradiation unit and ultraviolet rays are taken as an example of the active energy ray, but the present invention is not limited to this.

  By irradiating the ink droplets ejected on the paper 5 (recording medium 14) with ultraviolet rays, the ink droplets are cured and fixed on the paper 5 (recording medium 14).

  As shown in FIG. 1, the image forming apparatus 1 includes an image forming unit 2, a conveying unit 3, and the like inside the apparatus main body (housing). The recording medium 14 is fed one by one from the paper feeding unit 4 provided on the right side surface of the apparatus main body, and is conveyed to the conveyance path 305 of the conveyance unit 3 via the conveyance path 310. When the transport unit 3 transports the recording medium 14, the carriage 23 of the image forming unit 2 ejects ink while moving the required carriage, whereby an image is formed (recorded) on the recording medium 14. The The recorded matter (recording medium 14 on which an image is formed) is discharged onto a discharge tray 104 provided on the left side surface of the apparatus main body through a conveyance path 306.

  Further, the image forming apparatus 1 can also perform lamination printing in which images are laminated on the recording medium 14 by the number of layers. Here, the “number of layers” indicates the number of times the image is stacked when one image is formed and then the next layer is formed on the image. When forming the second and subsequent layers, the image forming apparatus 1 first returns the recording medium 14 to the conveyance path 310 by conveying the recording medium 14 in the order of the conveyance paths 306, 305, and 310. The image forming apparatus 1 transports the recording medium 14 returned to the transport path 310 in the order of the transport paths 310, 305, and 306, and further forms an image by the above-described image forming procedure. By repeating this, the image forming apparatus 1 forms an image with the required number of layers on the recording medium 14 and discharges the recorded matter indicating the required image onto the paper discharge tray 104.

  A carriage 23 that holds the recording head 24 is held by a guide rod 22 and a guide stay so as to be movable in the main scanning direction. The main scanning motor 27 moves and scans the carriage 23 in the main scanning direction via a timing belt 29 spanned between the driving pulley 28A and the driven pulley 28B.

  The carriage 23 can adjust the distance in the vertical direction between the recording head 24 and the recording medium 14 according to the number of target image layers, that is, according to the thickness of the ink.

  Further, the UV lamp 51 (52) is locked to the carriage 23 by a ball screw rod 53 (54) screwed in a spiral shape. The UV lamp 51 (52) can move along the ball screw rod 53 (54), and is disposed at a predetermined distance from the recording head 24.

  The UV lamps 51 and 52 move and scan in the main scanning direction together with the recording head 24. The scanning method of the image forming apparatus 1 of the embodiment is a shuttle type. That is, the image forming apparatus 1 moves the carriage 23 in the main scanning direction and feeds the recording medium 14 from the recording head 24 mounted on the carriage 23 while feeding the recording medium 14 in the paper transporting direction (sub-scanning direction) by the transport unit 3. To discharge. At the same time, the image forming apparatus 1 forms an image by curing ink droplets while irradiating ultraviolet rays with the UV lamps 51 and 52 mounted on the carriage 23.

  The recording head 24 is driven by, for example, a piezo type driving method. In the piezo-type drive system, a piezoelectric element is used as pressure generating means (actuator means) for pressurizing ink in the ink flow path (pressure generating chamber). The recording head 24 uses a piezoelectric element to deform a diaphragm that forms the wall surface of the ink flow path, and ejects ink droplets by changing the volume of the ink flow path.

  The driving method of the recording head 24 is not limited to the piezo method, and any driving method may be used. The drive method of the recording head 24 may be, for example, an electrostatic drive method. In the electrostatic drive system, the diaphragm and the electrode that form the wall surface of the ink flow path are arranged to face each other, and the diaphragm is deformed by an electrostatic force generated between the vibration plate and the electrode, whereby the ink flow path Ink droplets are ejected by changing the internal volume.

  As shown in FIG. 2, a maintenance / recovery mechanism 121 for maintaining and recovering the state of the nozzles of the recording head 24 is disposed in a non-printing area on one side of the carriage 23 in the scanning direction. The maintenance / recovery mechanism 121 includes moisturizing caps 122y, 122m, 122k, 122w, and 122c, a wiper member 124, an idle discharge receiving member 125, and the like. The moisturizing caps 122y, 122m, 122k, 122w and 122c cap the nozzle surfaces of the droplet discharge heads 24y, 24m, 24k, 24w and 24c, respectively. The wiper member 124 wipes the nozzle surfaces of the five droplet discharge heads 24y, 24m, 24k, 24w, and 24c. The idle discharge receiving member 125 is a member that receives the discharge (empty discharge) of droplets that do not contribute to recording (image formation).

  Further, in the non-printing area on the other side of the carriage 23 in the scanning direction, droplets that do not contribute to recording (image formation) (empty ejection) from the five droplet ejection heads 24y, 24m, 24k, 24w, and 24c. An empty discharge receiving member 126 for performing the above is disposed. The empty discharge receiving member 126 has five openings 127y, 127m, 127k, 127w, and 127c corresponding to the five droplet discharge heads 24y, 24m, 24k, 24w, and 24c.

  Note that the image forming apparatus 1 may include a maintenance unit that performs maintenance of each head of the carriage 23 as necessary. In this case, you may provide the waste liquid tank which collect | recovers the waste liquid discharged | emitted after a maintenance.

  The description of the tension roller 15, the paper discharge roller 16, the paper discharge roller 17, the transport roller 19, and the sub-scanning motor 131 included in FIG. Reference will be made later.

  Next, the conveyance unit 3 of the image forming apparatus 1 according to the embodiment will be described with reference to FIG.

  FIG. 3 is a schematic diagram illustrating an example of the conveyance unit 3 of the image forming apparatus 1 according to the embodiment. The conveyance unit 3 includes a conveyance belt 13 that adsorbs the recording medium 14 and conveys the recording medium 14 so as to face the image forming unit 2. The conveyor belt 13 is wound around the conveyor roller 19 and the driven roller 21 and is tensioned by the tension roller 15 so as to maintain an appropriate tension.

  The tension roller 15 is held by the arm 37b. The arm 37b is arranged so as to be able to rotate and move with the rotation fulcrum 37a as a fulcrum. Therefore, for example, the tension of the conveyor belt 13 can be adjusted by moving the tension roller 15 in the direction of the arrow shown in FIG. The sub-scanning motor 131 rotates the transport belt 13 by rotating the transport roller 19.

  Further, the position of the driven roller 21 can be changed, and the conveying surface formed by the conveying roller 19 and the driven roller 21 can be lowered, for example, by a distance a shown in FIG.

  The platen member 40 is disposed in order to guide the conveyance belt 13 in a region facing the image forming unit 2 and maintain appropriate flatness.

  The conveyor belt 13 preferably has a two-layer structure of a front layer and a back layer, for example. The surface layer is a medium resistance layer that becomes a sheet suction surface formed of a pure resin material that is not subjected to resistance control. A pure resin material not subjected to resistance control is, for example, ETFE pure material. The back layer is an earth layer made of the same material as the surface layer and subjected to resistance control by carbon. The transport belt 13 may have a one-layer structure or a structure having three or more layers.

  A pressure roller 38 that presses the recording medium 14 against the conveyance belt 13 at a position facing the conveyance roller 19 is disposed on the upstream side of the conveyance unit 3. The pressure roller 38 pressurizes the recording medium 14 to be in close contact with the conveyance belt 13, and attracts the recording medium 14 to the conveyance belt 13 by static electricity.

  Further, in order to charge the surface of the conveyor belt 13, a charging roller 18 is disposed upstream of the pressure roller 38 in the circumferential direction of the conveyor belt 13. The charging roller 18 is charged by supplying a DC voltage or a high voltage in which an alternating current is superimposed on a direct current from a high-voltage power supply (DC or a superimposed bias supply unit of DC and AC).

  On the other hand, a paper discharge mechanism having a paper discharge roller 16, a paper discharge roller 17, and a paper discharge tray 104 is disposed downstream of the transport unit. The paper discharge roller 16 performs conveyance for discharging the recording medium 14. The paper discharge roller 17 presses the recording medium 14. The paper discharge tray 104 stocks the discharged recording medium 14.

  Next, an example of the configuration of the control unit of the image forming apparatus 1 according to the embodiment will be described with reference to FIG.

  FIG. 4 is a diagram illustrating an example of the configuration of the control unit 200 of the image forming apparatus 1 according to the embodiment. The control unit 200 of the image forming apparatus 1 according to the embodiment includes a CPU 201, a ROM 202, a RAM 203, an NVRAM 204, an ASIC 205, a scanner control unit 206, an external I / F 207, a head drive control unit 208, a head driver 209, motor drive units 211 to 215, A clutch drive unit 216, an AC bias supply unit 217, an I / O 221, a motor drive unit 317, a curl correction (drying) control unit 311, a suction conveyance control unit 312, and a lamp unit control unit 313 are provided.

  The control unit 200 includes sensors such as the operation panel 222, the image reading unit 11, and the temperature / humidity sensor 300, the recording head 24, the main scanning motor 27, the sub-scanning motor 131, the paper feed motor 45, the paper discharge motor 271, and double-sided conveyance. The motor 291, the clutches 241, the charging roller 18, the transport motor 318, the heater 425, the fan 426, the pressure roller 38, and the fan 424 are connected.

  The CPU 201 executes a program that controls the operation of the image forming apparatus 1. The ROM 202 stores programs, drive waveform data, and other fixed data. The RAM 203 temporarily stores image data and the like. The NVRAM 204 is a non-volatile memory that stores data that needs to be held even when the power of the image forming apparatus 1 is shut off. The ASIC 205 processes image processing on image data and input / output signals for controlling the image forming apparatus 1. The image processing on the image data includes, for example, various signal processing and image data rearrangement processing.

  The external I / F 207 transmits / receives data and signals to / from an external device.

  The head drive control unit 208 and the head driver 209 drive and control the recording head 24 of the image forming unit 2. The motor driving unit 211 controls the driving of the main scanning motor 27. The motor driving unit 212 controls driving of the sub-scanning motor 131. The motor driving unit 213 controls driving of the paper feed motor 45. The motor control unit 214 controls driving of the paper discharge motor 271. The motor control unit 215 drives and controls the double-sided conveyance motor 291.

  The AC bias supply unit 217 drives and controls the charging roller 18 by applying an AC bias to the charging roller 18.

  The I / O 221 includes a temperature / humidity sensor 300 that detects environmental temperature and environmental humidity (whichever one may be used), an encoder that outputs a detection signal corresponding to the moving amount and moving speed of the conveyor belt 13, and other sensors. From, a detection signal is received.

  The operation panel 222 is an operation unit that inputs and outputs information.

  The motor driving unit 317 drives and controls a conveyance motor 318 that conveys the recording medium 14. The curl correction (drying) control unit 311 controls the heater 425 and the fan 426 used for the curl correction (drying) process. The suction conveyance control unit 312 controls the pressure roller 38 and the fan 424 used for the suction conveyance process. The lamp unit controller 313 controls the lighting of the UV lamps 51 and 52.

  Next, the operation flow of the control unit 200 will be described.

  First, the external I / F 207 receives print data and the like from an information processing device such as a personal computer, an image reading device such as an image scanner, and a host device such as an imaging device such as a digital camera via a cable and a network. Receive. The image reading apparatus may be the image reading unit 11 controlled by the scanner control unit 206, for example.

  Next, the CPU 201 reads out and analyzes the print data in the reception buffer included in the external I / F 207. Next, the ASIC 205 generates dot pattern data by performing image processing on the print data. The ASIC 205 transmits dot pattern data to the head drive control unit 208 in synchronization with the clock signal. The dot pattern data indicates a dot pattern formed by droplets ejected from the droplet ejection heads 24y, 24m, 24k, 24w, and 24c.

  FIG. 5 is a diagram illustrating an example of the configuration of the head drive control unit 208 of the image forming apparatus 1 according to the embodiment. The head drive control unit 208 according to the embodiment includes a reception unit 501, an order determination unit 502, an assignment determination unit 503, and a transmission unit 504.

  The accepting unit 501 accepts dot pattern data from the ASIC 205.

  The order determining unit 502 determines the order of dot pattern data formation. Specifically, the order determining unit 502 first divides the dot pattern data into partial dot pattern data indicating a plurality of partial dot patterns that are a part of the dot pattern data. Next, the order determination unit 502 determines the formation order of a plurality of partial dot patterns based on the dot arrangement data. The dot arrangement data is data for determining the formation order of the dot pattern indicated by the dot pattern data. The dot arrangement data may be arbitrarily determined.

  For each partial dot pattern, the allocation determining unit 503 forms the partial dot pattern by using a plurality of first nozzles of the droplet discharge head 24y (24m, 24k, 24w, 24c) or the droplet discharge head 24y ( 24m, 24k, 24w, 24c) are assigned to a plurality of second nozzles. The assignment determining unit 503 assigns at least the formation of the final dot pattern to the plurality of second nozzles of the droplet discharge head 24y (24m, 24k, 24w, 24c). The final dot pattern is a partial dot pattern formed last in a unit area that is a unit of image formation. The description of the first nozzle and the second nozzle will be described later.

  The transmission unit 504 transmits head drive control information including a plurality of partial dot pattern data, a forming order of the plurality of partial dot pattern data, and information indicating nozzles that form the plurality of partial dot pattern data to the head driver 209. Send to.

  Returning to FIG. 4, the head driver 209 then receives head drive control information from the head drive control unit 208. The head driver 209 operates the actuator of the recording head 24 based on the head drive control information. The actuator of the recording head 24 selectively applies the drive waveform to the required droplet discharge head 24y (24m, 24k, 24w, 24c), thereby selectively driving the required droplet discharge head 24y (24m, 24k, 24w, 24c). ) Droplets are ejected from the nozzle.

  Next, the CPU 201 transmits irradiation control data for controlling the UV lamps 51 and 52 to the lamp unit control unit 313. Next, the lamp unit controller 313 controls the UV lamps 51 and 52 based on the irradiation control data. Next, the UV lamps 51 and 52 irradiate ultraviolet curable ink (active energy ray curable ink) discharged from the droplet discharge head 24y (24m, 24k, 24w, 24c). As a result, an image is formed (recorded) on the recording medium 14.

  In the image forming apparatus 1 configured as described above, the recording medium 14 is fed one by one from the sheet feeding unit 4 as described above. The recording medium 14 is pressed against the transport belt 13 by the pressure roller 38 and transported. Then, the recording medium 14 is electrostatically attracted to the conveyance belt 13, and the recording medium 14 is conveyed in the sub-scanning direction by the circumferential movement of the conveyance belt 13.

  Then, the head drive control unit 208 drives the recording head 24 based on the image signal (dot pattern data) while the main scanning motor 27 moves the carriage 23. The recording head 24 discharges ink droplets to the recording medium 14 that is stopped, and records a dot pattern for one scan on the recording medium 14. When recording for one scan is completed, the sub-scanning motor 131 rotates the transport roller 19 to rotate the transport belt 13 to move the recording medium 14 in the sub-scan direction by the number of lines corresponding to one scan. send. In this way, the image forming apparatus 1 intermittently conveys the recording medium 14 to form an image.

  The CPU 201 ends the recording operation upon receiving a recording end signal or a signal that the trailing end of the recording medium 14 has reached the recording area. The recording medium 14 on which the image is formed is sent out to a paper discharge tray 104 which is a transport destination.

  In the description of the above-described embodiment, an example in which the conveyance belt 13 that performs electrostatic adsorption is used as the conveyance unit has been described. However, a conveyance belt that performs adsorption by a suction fan can also be used. Further, a configuration may be adopted in which the sheet is conveyed opposite to the image forming unit 2 by the conveyance roller 19 and the pressure roller 38 without using the conveyance belt 13.

  Next, details of a printed matter production method by the image forming apparatus 1 of the embodiment will be described.

  First, the relationship between the dot height of ink droplets of ultraviolet curable ink and the time from ink landing to UV irradiation will be described.

  First, with reference to FIG. 6 and FIG. 7A, image unevenness (hereinafter referred to as “bidirectional unevenness”) due to bidirectional printing, which is a problem of the prior art, will be described.

  FIG. 6 is a diagram showing the relationship between the dot height of ink droplets of ultraviolet curable ink and the time from ink landing to UV irradiation.

  FIG. 6 shows the dot height when the ejection amount of one droplet ejected from one nozzle of the recording head 24 is a large droplet (14 pl), the dot height when it is a small droplet (5 pl), and from ink landing to UV irradiation. Shows the relationship with the time. The dot height indicates the dot height of an ink droplet when a 14 pl (5 pl) ink droplet is ejected onto the recording medium 14 (on the same ink ejected first). The ultraviolet curable ink can be printed even when the recording medium 14 is a non-penetrable medium, but has a feature that ink droplets are likely to spread.

  Since the ink droplets ejected on the recording medium 14 spread over time, the spread of the ink droplets on the recording medium 14 varies depending on the time from ink landing to UV irradiation. As a result, the ink height of the ink droplet changes as shown in FIG.

  For this reason, if the distance between the UV lamp 51 (52) and the droplet discharge head 24y (24m, 24k, 24w, 24c) is different between the forward path and the backward path, the time from ink landing to UV irradiation is different. The ink height of the ink droplet ejected in the forward path is different from the height of the ink droplet ejected in the backward path. The difference between the ink height of the ink droplet ejected in the forward path and the height of the ink droplet ejected in the backward path is particularly a gloss difference. Due to this gloss difference, bidirectional unevenness of the image occurs.

  Here, the bidirectional unevenness that occurs when the droplet discharge heads 24y, 24m, 24k, 24w, and 24c are arranged as shown in FIG. 2 will be described. In the example of FIG. 2, the droplet discharge head 24 k that discharges black (Bk) ink is disposed at the center of the carriage 23. Accordingly, the distance X1 between the black (Bk) ink droplet discharge head 24k and the UV lamp 51 and the distance X2 between the black (Bk) ink droplet discharge head 24k and the UV lamp 52 become the same. Therefore, in the case of black (Bk) ink, the time from ink landing to UV irradiation is the same for the forward path and the backward path, and no bidirectional unevenness occurs.

  However, in the case of white (W) ink, cyan (C) ink, magenta (M) ink, and yellow (Y) ink, bidirectional unevenness occurs because the time from ink landing to UV irradiation differs between the forward path and the backward path. .

  FIG. 7A is a schematic diagram illustrating an example of a cross section of an image formed by ink droplets formed on a recording medium 14 by conventional bidirectional printing. The example of FIG. 7A is a schematic diagram of an image cross section when yellow (Y) ink is ejected in the order of the forward path (A), the backward path (B), and the forward path (C) by the image forming unit 2 illustrated in FIG. . As shown in FIG. 7A, the dot height and area of the ink droplets ejected in the forward paths (A) and (C) are different from the dot height and area of the ink droplets ejected in the return path (B). For this reason, the dot height and the area differ between the forward paths (A) and (C) and the backward path (B) of the recording head, and bidirectional unevenness occurs in the image formed on the recording medium 14.

  This bidirectional unevenness is significantly affected by the unevenness of the top ink formed last in the unit area where the image is formed. In other words, the influence of the partial dot pattern not formed last in the unit area where the image is formed is smaller than the influence of the final dot pattern formed last in the unit area where the image is formed.

  In the image forming method of the embodiment, the last dot pattern formed last in the unit area where the image is formed is printed in one direction of either the forward path or the backward path.

  FIG. 7B is a schematic diagram illustrating an example of a cross section of an image formed by ink droplets formed on the recording medium 14 by the image forming method of the embodiment. The example of FIG. 7B shows a case where the last dot pattern formed last in the unit area where the image is formed is ejected in the forward direction. As shown in FIG. 7B, the dot height and the difference in dot height can be made smaller than in FIG. 7A. Thereby, according to the image forming method of the embodiment, bidirectional unevenness generated in an image formed on the recording medium 14 can be suppressed as compared with the conventional case.

  FIG. 7C is a schematic diagram illustrating an example of a cross section of an image formed by ink droplets formed on the recording medium 14 by the image forming method of the embodiment. The example of FIG. 7C shows a case where the last dot pattern formed last in the unit area where the image is formed is ejected in the backward direction. As shown in FIG. 7C, the dot height and the difference in dot height can be made smaller than in FIG. 7A. Thereby, according to the image forming method of the embodiment, bidirectional unevenness generated in an image formed on the recording medium 14 can be suppressed as compared with the conventional case.

  Next, details of the image forming method of the embodiment will be described. In the description of the embodiment, a case will be described in which the last dot pattern formed last in the unit area where the image is formed is formed in the forward path. Hereinafter, a description will be given comparing the conventional image forming method with substantially equal pitch feeding and the image forming method with substantially equal pitch feeding in the embodiment. In the image forming method with substantially equal pitch feeding, the influence of nozzle defects (bending, non-ejection, etc.) can be dispersed, so that the influence of nozzle defects can be made inconspicuous.

<1 pass, 1/2 interlace>
First, the case where the image forming method is 1 pass and 1/2 interlace will be described as an example. In the case of 1 pass and 1/2 interlace, the droplet discharge head 24y (24m, 24k, 24w, 24c) scans once in the main scanning direction and scans twice in the sub scanning direction for each unit area. An image is formed by performing.

  In order to explain the difference between the image forming method of the embodiment and the image forming method of the prior art, first, the conventional image forming method will be described.

  8A to 8C are diagrams illustrating an example of a conventional image forming method (1 pass, 1/2 interlace). 8A to 8C show a case where the droplet discharge head 24y discharges yellow (Y) ink. The same applies to inks other than yellow (Y) ink. 8A to 8C show a case where the size of the image printed on the recording medium 14 is 8 pixels in the main scanning direction and 24 pixels in the sub scanning direction.

  In the case of 1/2 interlace, in the conventional image forming method, the nozzles of the droplet discharge head 24y are divided into approximately two equal parts to print an image. Therefore, in the example of FIGS. 8A to 8C, since the nozzles of the droplet discharge head 24 y are 12, 6 nozzles are used as the first nozzle 601 and 6 nozzles are used as the second nozzle 602. As a result, the unit area for image formation is 8 pixels in the main scanning direction and 12 pixels in the sub-scanning direction. 8A to 8C show a case where the nozzle density of the droplet discharge head 24y is ½ of the image density.

  In the first scan, the first nozzle 601 of the droplet discharge head 24y forms a partial dot pattern 601a on the recording medium 14 (see FIG. 8A). In the second scan, the first nozzle 601 of the droplet discharge head 24y forms a partial dot pattern 601b on the recording medium 14 (see FIG. 8B). In the second scan, the second nozzle 602 of the droplet discharge head 24y forms a partial dot pattern 602a on the recording medium 14 (see FIG. 8B). In the third scan, the second nozzle 602 of the droplet discharge head 24y forms a partial dot pattern 602b on the recording medium 14 (see FIG. 8C).

  8A to 8C, an image is formed on the recording medium 14 by the partial dot patterns 601a, 601b, 602a, and 602b. In this case, the partial dot pattern 602a and the partial dot pattern 602b indicate the final dot pattern (image formed on the uppermost layer) formed last in the unit area. As described above, the bidirectional unevenness occurs due to the difference in the spread of the ink droplets ejected on the top of the image. Since the partial dot pattern 602a is printed in the backward path and the partial dot pattern 602b is printed in the forward path, bidirectional unevenness occurs in the image printed on the recording medium 14.

  On the other hand, FIGS. 9A to 9E are diagrams illustrating an example of the image forming method (1 pass, 1/2 interlace) of the embodiment. 9A to 9E show a case where the droplet discharge head 24y discharges yellow (Y) ink. The same applies to inks other than yellow (Y) ink. 9A to 9E show a case where the size of the image printed on the recording medium 14 is 8 pixels in the main scanning direction and 24 pixels in the sub scanning direction.

  In the case of ½ interlace, in the image forming method of the embodiment, the nozzles of the droplet discharge head 24y are divided into approximately three equal parts, and the ratio of the first nozzle 701 and the second nozzle 702 is divided by 1: 2. To do. The example of FIGS. 9A to 9E shows a case where 4 nozzles are used as the first nozzle 701 and 8 nozzles are used as the second nozzle 702. In the image forming method of the embodiment, the second nozzle 702 ejects ink droplets onto the recording medium 14 when the droplet ejection head 24y moves in one direction of the forward path or the backward path. In the example of FIGS. 9A to 9E, the second nozzle 702 ejects ink droplets onto the recording medium 14 when the droplet ejection head 24y moves in the forward path. The reason for dividing the ratio between the first nozzle 701 and the second nozzle 702 to 1: 2 is that the second nozzle 702 ejects ink droplets when moving in one direction of the forward path or the backward path. Because. 9A to 9E, the unit area for image formation is 8 pixels in the main scanning direction and 8 pixels in the sub-scanning direction (see FIG. 9E). 9A to 9E show a case where the density of the nozzles of the droplet discharge head 24y is ½ of the image density.

  In the first scan, the first nozzle 701 of the droplet discharge head 24y forms a partial dot pattern 701a on the recording medium 14 (see FIG. 9A). In the second scan, the first nozzle 701 of the droplet discharge head 24y forms a partial dot pattern 701b on the recording medium 14 (see FIG. 9B).

  In the third scan, the second nozzle 702 of the droplet discharge head 24y forms a partial dot pattern 702a on the recording medium 14 (see FIG. 9C). As a result, an image of a unit region of 8 pixels in the main scanning direction and 16 pixels in the sub-scanning direction is completed. In the third scan, the first nozzle 701 of the droplet discharge head 24y forms a partial dot pattern 701c on the recording medium 14 (see FIG. 9C).

  Since the fourth scan is a return pass, the second nozzle 702 of the droplet discharge head 24y does not form an image on the recording medium 14 (see FIG. 9D). In the fifth scan, the second nozzle 702 of the droplet discharge head 24y forms a partial dot pattern 702b on the recording medium 14 (see FIG. 9E).

  9A to 9E, an image is formed on the recording medium 14 by the partial dot patterns 701a, 701b, 701c, 702a, and 702b. In this case, the partial dot pattern 702a and the partial dot pattern 702b indicate the final dot pattern (image formed on the uppermost layer) formed last in the unit area. As described above, the bidirectional unevenness occurs due to the difference in the spread of the ink droplets ejected on the top of the image. In the image forming method of the embodiment, since the partial dot patterns 702a and 702b are both printed in the forward path, it is possible to suppress the influence of bidirectional unevenness that occurs in the image printed on the recording medium 14 as compared to the conventional case. .

<In case of 2 passes>
Next, the case where the image forming method is two passes will be described as an example. In the case of two passes, the droplet discharge head 24y (24m, 24k, 24w, 24c) performs scanning twice in the main scanning direction and scanning once in the sub-scanning direction for each unit region. Is formed.

  In order to explain the difference between the image forming method of the embodiment and the image forming method of the prior art, first, the conventional image forming method will be described.

  10A to 10C are diagrams illustrating an example of a conventional image forming method (two passes). 10A to 10C show a case where the droplet discharge head 24y discharges yellow (Y) ink. The same applies to inks other than yellow (Y) ink. 10A to 10C show a case where the size of the image printed on the recording medium 14 is 8 pixels in the main scanning direction and 12 pixels in the sub scanning direction.

  In the case of two passes, in the conventional image forming method, an image is printed by dividing the nozzle of the droplet discharge head 24y into approximately two equal parts. Therefore, in the example of FIGS. 10A to 10C, since the nozzles of the droplet discharge head 24y are 12, 6 nozzles are used as the first nozzle 601 and 6 nozzles are used as the second nozzle 602. As a result, the unit area for image formation is 8 pixels in the main scanning direction and 6 pixels in the sub-scanning direction. 10A to 10C show the case where the nozzle density of the droplet discharge head 24y is the same as the image density.

  In the first scan, the first nozzle 601 of the droplet discharge head 24y forms a partial dot pattern 601a on the recording medium 14 (see FIG. 10A). In the second scan, the first nozzle 601 of the droplet discharge head 24y forms a partial dot pattern 601b on the recording medium 14 (see FIG. 10B). In the second scan, the second nozzle 602 of the droplet discharge head 24y forms a partial dot pattern 602a on the recording medium 14 (see FIG. 10B). In the third scan, the second nozzle 602 of the droplet discharge head 24y forms a partial dot pattern 602b on the recording medium 14 (see FIG. 10C).

  10A to 10C, an image is formed on the recording medium 14 by the partial dot patterns 601a, 601b, 602a, and 602b. In this case, the partial dot pattern 602a and the partial dot pattern 602b indicate the final dot pattern (image formed on the uppermost layer) formed last in the unit area. As described above, the bidirectional unevenness occurs due to the difference in the spread of the ink droplets ejected on the top of the image. Since the partial dot pattern 602a is printed in the backward path and the partial dot pattern 602b is printed in the forward path, bidirectional unevenness occurs in the image printed on the recording medium 14.

  On the other hand, FIGS. 11A to 11E are diagrams illustrating an example of the image forming method (two passes) of the embodiment. 11A to 11E show a case where the droplet discharge head 24y discharges yellow (Y) ink. The same applies to inks other than yellow (Y) ink. 11A to 11E show a case where the size of the image printed on the recording medium 14 is 8 pixels in the main scanning direction and 12 pixels in the sub scanning direction.

  In the case of two passes, in the image forming method of the embodiment, the nozzles of the droplet discharge head 24y are divided into approximately three equal parts, and the ratio between the first nozzle 701 and the second nozzle 702 is divided by 1: 2. The example of FIGS. 11A to 11E shows a case where 4 nozzles are used as the first nozzle 701 and 8 nozzles are used as the second nozzle 702. In the image forming method of the embodiment, the second nozzle 702 ejects ink droplets onto the recording medium 14 when the droplet ejection head 24y moves in one direction of the forward path or the backward path. In the example of FIGS. 11A to 11E, the second nozzle 702 ejects ink droplets onto the recording medium 14 when the droplet ejection head 24y moves in the forward path. The reason for dividing the ratio between the first nozzle 701 and the second nozzle 702 to 1: 2 is that the second nozzle 702 ejects ink droplets when moving in one direction of the forward path or the backward path. Because. 11A to 11E, the unit area for image formation is 8 pixels in the main scanning direction and 8 pixels in the sub-scanning direction (see FIG. 11E). 11A to 11E show a case where the nozzle density of the droplet discharge head 24y is the same as the image density.

  In the first scan, the first nozzle 701 of the droplet discharge head 24y forms a partial dot pattern 701a on the recording medium 14 (see FIG. 11A). In the second scan, the first nozzle 701 of the droplet discharge head 24y forms a partial dot pattern 701b on the recording medium 14 (see FIG. 11B).

  In the third scan, the second nozzle 702 of the droplet discharge head 24y forms a partial dot pattern 702a on the recording medium 14 (see FIG. 11C). As a result, an image of a unit region of 8 pixels in the main scanning direction and 8 pixels in the sub-scanning direction is completed. In the third scan, the first nozzle 701 of the droplet discharge head 24y forms a partial dot pattern 701c on the recording medium 14 (see FIG. 11C).

  Since the fourth scan is a return path, the second nozzle 702 of the droplet discharge head 24y does not form an image on the recording medium 14 (see FIG. 11D). In the fifth scan, the second nozzle 702 of the droplet discharge head 24y forms a partial dot pattern 702b on the recording medium 14 (see FIG. 11E).

  In the example of FIGS. 11A to 11E, an image is formed on the recording medium 14 by the partial dot patterns 701a, 701b, 701c, 702a, and 702b. In this case, the partial dot pattern 702a and the partial dot pattern 702b indicate the final dot pattern (image formed on the uppermost layer) formed last in the unit area. As described above, the bidirectional unevenness occurs due to the difference in the spread of the ink droplets ejected on the top of the image. In the image forming method of the embodiment, since the partial dot patterns 702a and 702b are both printed in the forward path, it is possible to suppress the influence of bidirectional unevenness that occurs in the image printed on the recording medium 14 as compared to the conventional case. .

  FIG. 12 is a flowchart illustrating an example of the image forming method of the embodiment. The flowchart of FIG. 12 shows an example of the image forming method of the embodiment for one unit area on the recording medium 14. First, the transport unit 3 transports the recording medium 14 (step S1). Next, based on the above-described head drive control information received from the head drive control unit 208 by the head driver 209, the partial dot pattern ejected to the unit area in the scanning in the main scanning direction is the final dot pattern (the relevant It is determined whether it is the last partial dot pattern formed in the unit area (step S2).

  When the pattern is not the final dot pattern (No in step S2), the first nozzle 701 ejects a partial dot pattern to the unit area while moving in the main scanning direction (forward path or backward path) according to the control of the head driver 209. (Step S3). Next, the process returns to step S1.

  If it is the final dot pattern (step S2, Yes), the head driver 209 determines whether or not the traveling direction in the main scanning direction is the forward path (step S4). If the traveling direction in the main scanning direction is not the forward path (step S4, No), the process returns to step S1. When the advancing direction in the main scanning direction is the forward path (step S4, Yes), the second nozzle 702 moves in the main scanning direction (forward path) according to the control of the head driver 209 while partially moving in the unit area. A dot pattern is discharged (step S5).

  Finally, an example of the effect of the image forming method of the embodiment will be described.

  FIG. 13 is a diagram for explaining the effect of the image forming method of the embodiment. The horizontal axis in FIG. 13 indicates lines in the sub-scanning direction. The n-line area indicates an n-th line area in the sub-scanning direction. Note that n is a plurality of integers. The vertical axis in FIG. 13 indicates the glossiness (60-degree glossiness).

  FIG. 13 shows the glossiness when black (Bk) ink is discharged at the position of the droplet discharge head 24y that discharges yellow (Y) ink in FIG. 2 in order to show the effect of the image forming method of the embodiment remarkably. The measurement results are shown. In FIG. 13, the image forming method (1 pass, 1/2 interlace) in which the influence of bidirectional unevenness is most likely to appear is the same as the conventional image forming method (see FIGS. 8A to 8C) and the image forming method of the embodiment. (See FIGS. 9A to 9E) and the measurement results are compared. For reference, FIG. 13 also shows a measurement result of unidirectional printing that is printed in one direction of the forward path.

  A graph 551 shows the glossiness of an image printed by unidirectional printing. In the case of unidirectional printing, all the images in the n-line region, the n + 1-line region, and the n + 2-line region are printed in the forward path, so the glossiness of the image for each line in the sub-scanning direction is constant. However, when an image is printed by unidirectional printing, it takes more time than when an image is printed by bidirectional printing.

  A graph 552 shows the glossiness of an image printed by the above-described conventional image forming method (1 pass, 1/2 interlace). For example, when n = 1, the images of the 1-line area and 3-line area are formed by the first scanning (outward path). The image of the two-line area is formed by the second scanning (return path). The difference between the glossiness (about 5.5) of the 1-line area and the 3-line area printed in the forward path and the glossiness (about 9.5) of the 2-line area printed in the backward path is 4.

  A graph 553 shows the glossiness of an image printed by the image forming method (1 pass, 1/2 interlace) of the above-described embodiment. For example, when n = 1, the images of the 1-line area and 3-line area are formed by the first scanning (outward path). The image of the two-line area is formed by the third scanning (outward path). The difference between the glossiness (about 5.5) of the 1-line area and the 3-line area printed in the forward path and the glossiness (about 6) of the 2-line area printed in the forward path is 0.5. Images with a gloss difference of 0.5 are at a level where even if they are adjacent, the difference in gloss is hardly visible. It can be seen that according to the image forming method (1 pass, 1/2 interlace) of the embodiment, the bidirectional unevenness of the image can be reduced as compared with the conventional image forming method (1 pass, 1/2 interlace).

  As described above, in the image forming apparatus 1 according to the embodiment, the final dot pattern formed last in the unit region of the unit in which the image is formed is the forward or backward pass in the main scanning direction by the second nozzle 702. It is discharged in one direction.

  Thus, according to the image forming apparatus 1 of the embodiment, it is possible to form a higher quality image with higher productivity than in the case of unidirectional printing. Specifically, in the example of the embodiment described above, the conventional bidirectional printing forms an image in units of 6 nozzles, whereas the image forming method of the embodiment forms an image in units of 4 nozzles. Therefore, the productivity of the image forming method of the embodiment is 2/3 of the conventional bidirectional printing. However, since the productivity of the conventional one-way printing is ½ of the productivity of the conventional bidirectional printing, the productivity of the image forming method of the embodiment is higher than the productivity of the conventional one-way printing.

  In addition, according to the image forming apparatus 1 of the embodiment, it is possible to easily reduce the bidirectional unevenness of the image that occurs during bidirectional printing at low cost.

  In the description of the image forming method of the above-described embodiment, the case of 1 pass, 1/2 interlace and the case of 2 pass have been described. However, by combining the case of 1-pass / 1/2 interlace and the case of 2-pass, the image forming method of the embodiment can be carried out to any image forming method by substantially equal pitch feeding.

  Specifically, the number of second nozzles 702 that print the final dot pattern formed last in the unit area of the unit in which the image is formed is doubled as the number of nozzles in the other nozzle areas. Then, the second nozzle 702 forms an image twice as long during the forward pass instead of forming an image during the return pass. The method can be carried out.

  In the description of the above-described embodiment, the case where the second nozzle 702 ejects the ink droplet that forms the final dot pattern formed last in the unit region has been described. However, the second nozzle 702 may eject ink droplets that form a partial dot pattern other than the final dot pattern. Thereby, the image forming apparatus 1 can form a higher quality image.

  In the description of the above-described embodiment, the case where the second nozzle 702 prints the last dot pattern formed last in the unit area in the forward path has been described. However, the image forming apparatus 1 may switch the main scanning direction (forward path or backward path) when forming the last dot pattern formed last in the unit area in accordance with the glossiness designation.

  The glossiness of an image will be described by taking the case of a cross section of an image using yellow (Y) ink (see FIG. 6) as an example. For example, when it is desired to make an area where yellow (Y) ink is used relatively low glossy, the final dot pattern to be formed last is the second nozzle 702 which can increase the dot height. When discharged, the area can be made low gloss. Also, for example, when it is desired to make a region where a relatively large amount of yellow (Y) ink is used highly glossy, the final dot pattern formed last in the return path in which the second nozzle 702 can reduce the dot height. When this is discharged, the area can be made highly glossy.

  The method for selecting the ink for designating the glossiness may be arbitrary. For example, glossiness information (low glossiness or high glossiness) indicating the glossiness of the color of the active energy ray curable ink may be received from the operation panel 222, a personal computer connected to the external I / F 207, or the like. Specifically, low gloss indicates a case where the gloss level is equal to or less than a threshold value. High gloss indicates a case where the gloss level is larger than the threshold value.

  Also, the dot height of inks other than yellow (Y) ink increases as the time from ink landing to UV irradiation becomes shorter due to the relationship between the dot height and the time from ink landing to UV irradiation (see FIG. 6). .

  Specifically, when it is desired to make yellow (Y) and magenta (M) in FIG. 2 low gloss, the second nozzle 702 forms yellow when forming the final dot pattern formed last in the unit area. (Y) Ink and magenta (M) ink are ejected in the forward path. When it is desired to make white (W) and cyan (C) low gloss, when the second nozzle 702 forms the final dot pattern formed last in the unit area, white (W) ink and cyan (C ) Print ink on the forward path. Note that black (Bk) is arranged at the center of the recording head 24. For this reason, the glossiness of black (Bk) is the same regardless of whether the second nozzle 702 ejects black (Bk) ink in either the forward path or the backward path.

  In addition, the image forming apparatus 1 receives direction information indicating the traveling direction (forward path or backward path) of the recording head 24 when forming the final dot pattern formed last in the unit area from the user via the operation panel 222. You may accept by input. As a result, when the glossiness setting of the image is unknown, for example, the user can print the last dot pattern formed last in the unit area by forming the last dot pattern and the last in the unit area. It is possible to compare the printed image by forming the final dot pattern to be formed in the backward path.

  In printing using ultraviolet curable ink, a lamination printing method is known in which an image is further printed on the image. The image forming apparatus 1 may accept information indicating an image to be stacked and printed by an input from the user via the operation panel 222. At this time, when the image forming apparatus 1 receives an input indicating setting of laminated printing and gloss control (low gloss or high gloss) from the user, the image forming method of the embodiment is performed on, for example, an image printed at the top. . As a result, even when the image forming apparatus 1 performs multi-layer printing of images, it is possible to reduce the time required for image formation and reduce bidirectional unevenness of the image.

  The recording medium 14 described above is not limited to paper but may be any material. The recording medium 14 is not limited to a planar object such as paper, but may be a three-dimensional object. The image formed by the image forming apparatus 1 may be arbitrary. An image formed by the image forming apparatus 1 is, for example, a character, a figure, a pattern, or the like. The pattern may be a pattern formed by simply landing droplets on the recording medium 14. Ink is a general term for all liquids capable of image formation.

  In addition, the reception unit 501, the order determination unit 502, the allocation determination unit 503, and the transmission unit 504 described above may be realized by software or hardware such as an IC (Integrated Circuit). Further, the reception unit 501, the order determination unit 502, the allocation determination unit 503, and the transmission unit 504 described above may be realized by combining software and hardware.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image forming part 3 Conveying part 4 Feeding part 5 Paper 11 Image reading part 13 Conveying belt 14 Recording medium 15 Tension roller 16 Discharge roller 17 Discharge roller 18 Charging roller 19 Conveying roller 21 Followed roller 22 Guide Rod 23 Carriage 24 Recording head 25 Sub tank 26 Ink cartridge 27 Main scanning motor 28A Drive pulley 28B Driven pulley 29 Timing belt 38 Pressure roller 40 Platen member 45 Paper feed motor 51, 52 UV lamp 53, 54 Ball screw rod 104 Paper discharge tray 121 Maintenance / recovery mechanism 122 Moisturizing cap 124 Wiper member 125, 126 Empty discharge receiving member 127 Opening 131 Sub-scanning motor 200 Control unit 201 CPU
202 ROM
203 RAM
204 NVRAM
205 ASIC
206 Scanner control unit 207 External I / F
208 Head Drive Control Unit 209 Head Driver 211-215, 317 Motor Drive Unit 216 Clutch Drive Unit 217 AC Bias Supply Unit 221 I / O
222 Operation Panel 241 Clutch 271 Paper Discharge Motor 291 Double-sided Conveyance Motor 300 Temperature / Humidity Sensor 310 Conveyance Path 311 Curl Correction (Drying) Control Unit 312 Adsorption Conveyance Control Unit 313 Lamp Unit Control Unit 318 Conveyance Motor 424 Fan 425 Heater 426 Fan 501 Reception Unit 502 order determining unit 503 allocation determining unit 504 transmitting unit 601 nozzle

JP 2005-342970 A

Claims (12)

A recording head that moves in the main scanning direction on the recording medium;
Mounted on the recording head, when the recording head moves in the forward path in the main scanning direction and when the recording head moves in the backward path in the main scanning direction, the active energy ray curable ink is ejected to the recording medium. And a plurality of second nozzles that discharge the active energy ray-curable ink to the recording medium when the recording head moves in one of the forward path and the backward path in the main scanning direction. A droplet discharge head having a nozzle;
A first irradiation unit disposed behind the recording head in the forward direction and irradiating the active energy ray-curable ink discharged from the droplet discharge head with active energy rays;
A second irradiation unit that is arranged behind the recording head in the backward direction and irradiates the active energy ray-curable ink ejected from the droplet ejection head with active energy rays;
The dot pattern data indicating a dot pattern formed by droplets discharged from the droplet discharge head is divided into partial dot pattern data indicating a plurality of partial dot patterns that are a part of the dot pattern, and An order determining unit that determines the order of forming the partial dot patterns;
For each partial dot pattern, the formation of the partial dot pattern is assigned to the plurality of first nozzles or the plurality of second nozzles, and is finally formed at least in a unit region that is a unit for image formation. An assignment determination unit that assigns the plurality of second nozzles to form the final dot pattern indicating the partial dot pattern;
An operation unit that receives input of direction information indicating a traveling direction of the recording head when the plurality of second nozzles ejects the partial dot pattern;
The liquid droplet ejection head is an image forming apparatus that ejects the active energy ray-curable ink from the plurality of second nozzles onto the recording medium when the recording head moves in a direction indicated by the direction information . A recording head that moves in the main scanning direction on the recording medium;
Mounted on the recording head, when the recording head moves in the forward path in the main scanning direction and when the recording head moves in the backward path in the main scanning direction, the active energy ray curable ink is ejected to the recording medium. And a plurality of second nozzles that discharge the active energy ray-curable ink to the recording medium when the recording head moves in one of the forward path and the backward path in the main scanning direction. A droplet discharge head having a nozzle;
A first irradiation unit disposed behind the recording head in the forward direction and irradiating the active energy ray-curable ink discharged from the droplet discharge head with active energy rays;
A second irradiation unit that is arranged behind the recording head in the backward direction and irradiates the active energy ray-curable ink ejected from the droplet ejection head with active energy rays;
The dot pattern data indicating a dot pattern formed by droplets discharged from the droplet discharge head is divided into partial dot pattern data indicating a plurality of partial dot patterns that are a part of the dot pattern, and An order determining unit that determines the order of forming the partial dot patterns;
For each partial dot pattern, the formation of the partial dot pattern is assigned to the plurality of first nozzles or the plurality of second nozzles, and is finally formed at least in a unit region that is a unit for image formation. The final dot pattern forming the partial dot pattern comprises an allocation determining unit that allocates to the plurality of second nozzles;
If the plurality of second nozzles for ejecting color the active energy ray curable ink of light Sawado is below the threshold, where the recording head is moved forward in the main scanning direction, the active energy ray curable ink Discharging onto the recording medium ,
It said plurality of second nozzles before Symbol glossiness ejecting the active energy ray-curable ink is larger than the threshold color, when the recording head is moved backward in the main scanning direction, the active energy ray curable ink the images forming device that discharges the recording medium.   A recording head that moves in the main scanning direction on the recording medium;
  Mounted on the recording head, when the recording head moves in the forward path in the main scanning direction, and when the recording head moves in the backward path in the main scanning direction, the active energy ray-curable ink of a predetermined color is recorded in the recording head. When the recording head moves in one direction of either the forward path or the backward path in the main scanning direction, the active energy ray-curable ink having the same color as the predetermined color is recorded on the recording medium. A plurality of second nozzles for discharging to the liquid droplet discharge head;
  A first irradiation unit disposed behind the recording head in the forward direction and irradiating the active energy ray-curable ink discharged from the droplet discharge head with active energy rays;
  A second irradiation unit that is arranged behind the recording head in the backward direction and irradiates the active energy ray-curable ink ejected from the droplet ejection head with active energy rays;
  The dot pattern data indicating a dot pattern formed by droplets discharged from the droplet discharge head is divided into partial dot pattern data indicating a plurality of partial dot patterns that are a part of the dot pattern, and An order determining unit that determines the order of forming the partial dot patterns;
  For each partial dot pattern, the formation of the partial dot pattern is assigned to the plurality of first nozzles or the plurality of second nozzles, and is finally formed at least in a unit region that is a unit for image formation. An image forming apparatus comprising: an allocation determining unit that allocates the final dot pattern indicating the partial dot pattern to the plurality of second nozzles. The assignment determination unit assigns the formation of the partial dot pattern other than the final dot pattern to the plurality of first nozzles, and assigns the formation of the final dot pattern to the plurality of second nozzles;
The image forming apparatus according to any one of claims 1 to 3. When the droplet discharge head performs stacked printing in which a plurality of images are stacked and printed on the recording medium, the active energy ray-curable ink that forms the final dot pattern of at least the uppermost layer image is Discharging from the second nozzle;
The image forming apparatus according to claim 1. The number of the second nozzles is twice the number of the first nozzles.
The image forming apparatus according to claim 1. A recording head moving in a main scanning direction on a recording medium;
When a plurality of first nozzles of a droplet discharge head mounted on the recording head moves in the forward path in the main scanning direction, and when the recording head moves in a backward path in the main scanning direction Discharging the active energy ray-curable ink onto the recording medium;
When the plurality of second nozzles of the droplet discharge head mounted on the recording head move in one direction of either the forward path or the backward path in the main scanning direction, the active energy ray curable ink is Discharging to a recording medium;
An order determining unit divides dot pattern data indicating a dot pattern formed by droplets discharged from the droplet discharge head into partial dot pattern data indicating a plurality of partial dot patterns that are a part of the dot pattern. And determining the formation order of the plurality of partial dot patterns;
A first irradiation unit arranged behind the recording head in the forward direction irradiates the active energy ray-curable ink ejected from the droplet ejection head with active energy rays;
A second irradiating unit arranged behind the recording head in the backward direction irradiates the active energy ray-curable ink ejected from the droplet ejection head with active energy rays;
An allocation determination unit allocates the formation of the partial dot pattern to the plurality of first nozzles or the plurality of second nozzles for each of the partial dot patterns, and at least a unit region that is a unit of image formation Assigning the partial dot pattern formed last to the plurality of second nozzles;
A step of receiving an input of direction information indicating a traveling direction of the recording head when the plurality of second nozzles discharge the partial dot pattern;
Discharging the active energy ray-curable ink from the plurality of second nozzles to the recording medium when the droplet discharge head moves in the direction indicated by the direction information; and
A method for producing printed matter including   A recording head moving in a main scanning direction on a recording medium;
  When a plurality of first nozzles of a droplet discharge head mounted on the recording head moves in the forward path in the main scanning direction, and when the recording head moves in a backward path in the main scanning direction Discharging the active energy ray-curable ink onto the recording medium;
  When the plurality of second nozzles of the droplet discharge head mounted on the recording head move in one direction of either the forward path or the backward path in the main scanning direction, the active energy ray curable ink is Discharging to a recording medium;
  An order determining unit divides dot pattern data indicating a dot pattern formed by droplets discharged from the droplet discharge head into partial dot pattern data indicating a plurality of partial dot patterns that are a part of the dot pattern. And determining the formation order of the plurality of partial dot patterns;
  A first irradiation unit arranged behind the recording head in the forward direction irradiates the active energy ray-curable ink ejected from the droplet ejection head with active energy rays;
  A second irradiating unit arranged behind the recording head in the backward direction irradiates the active energy ray-curable ink ejected from the droplet ejection head with active energy rays;
  An allocation determination unit allocates the formation of the partial dot pattern to the plurality of first nozzles or the plurality of second nozzles for each of the partial dot patterns, and at least a unit region that is a unit of image formation Forming the partial dot pattern formed last includes assigning to the plurality of second nozzles;
  When the plurality of second nozzles of the droplet discharge head mounted on the recording head move in one direction of either the forward path or the backward path in the main scanning direction, the active energy ray curable ink is The step of discharging to the recording medium is as follows:
  When the plurality of second nozzles that discharge the active energy ray-curable ink having a color whose glossiness is equal to or less than a threshold value move the recording head in the main scanning direction, the active energy ray-curable ink is Discharging to a recording medium;
  The plurality of second nozzles that discharge the active energy ray-curable ink having a color whose glossiness is greater than a threshold value cause the active energy ray-curable ink to be discharged when the recording head moves in a return path in the main scanning direction. Discharging to a recording medium;
  A method for producing printed matter including   A recording head moving in a main scanning direction on a recording medium;
  When a plurality of first nozzles of a droplet discharge head mounted on the recording head moves in the forward path in the main scanning direction, and when the recording head moves in a backward path in the main scanning direction Discharging a predetermined color of active energy ray-curable ink onto the recording medium;
  When the plurality of second nozzles of the droplet discharge head mounted on the recording head move in one direction of either the forward path or the backward path in the main scanning direction, the activation energy of the same color as the predetermined color Discharging line curable ink onto the recording medium;
  An order determining unit divides dot pattern data indicating a dot pattern formed by droplets discharged from the droplet discharge head into partial dot pattern data indicating a plurality of partial dot patterns that are a part of the dot pattern. And determining the formation order of the plurality of partial dot patterns;
  A first irradiation unit arranged behind the recording head in the forward direction irradiates the active energy ray-curable ink ejected from the droplet ejection head with active energy rays;
  A second irradiating unit arranged behind the recording head in the backward direction irradiates the active energy ray-curable ink ejected from the droplet ejection head with active energy rays;
  An allocation determination unit allocates the formation of the partial dot pattern to the plurality of first nozzles or the plurality of second nozzles for each of the partial dot patterns, and at least a unit region that is a unit of image formation Assigning the partial dot pattern formed last to the plurality of second nozzles;
  A method for producing printed matter including A recording head that moves in the main scanning direction on the recording medium;
Mounted on the recording head, when the recording head moves in the forward path in the main scanning direction and when the recording head moves in the backward path in the main scanning direction, the active energy ray curable ink is ejected to the recording medium. And a plurality of second nozzles that discharge the active energy ray-curable ink to the recording medium when the recording head moves in one of the forward path and the backward path in the main scanning direction. A droplet discharge head having a nozzle;
A first irradiation unit disposed behind the recording head in the forward direction and irradiating the active energy ray-curable ink discharged from the droplet discharge head with active energy rays;
An image forming apparatus comprising: a second irradiation unit that is disposed behind the recording head in the return path direction and irradiates the active energy ray-curable ink discharged from the droplet discharge head with active energy rays.
The dot pattern data indicating a dot pattern formed by droplets discharged from the droplet discharge head is divided into partial dot pattern data indicating a plurality of partial dot patterns that are a part of the dot pattern, and An order determining unit that determines the order of forming the partial dot patterns;
For each partial dot pattern, the formation of the partial dot pattern is assigned to the plurality of first nozzles or the plurality of second nozzles, and is finally formed at least in a unit region that is a unit for image formation. The partial dot pattern is formed by an allocation determining unit that is allocated to the plurality of second nozzles;
The plurality of second nozzles function as an operation unit that receives input of direction information indicating a traveling direction of the recording head when the partial dot pattern is ejected;
A program for causing the liquid droplet ejection head to eject the active energy ray-curable ink from the plurality of second nozzles onto the recording medium when the recording head moves in a direction indicated by the direction information .   A recording head that moves in the main scanning direction on the recording medium;
  Mounted on the recording head, when the recording head moves in the forward path in the main scanning direction and when the recording head moves in the backward path in the main scanning direction, the active energy ray curable ink is ejected to the recording medium. And a plurality of second nozzles that discharge the active energy ray-curable ink to the recording medium when the recording head moves in one of the forward path and the backward path in the main scanning direction. A droplet discharge head having a nozzle;
  A first irradiation unit disposed behind the recording head in the forward direction and irradiating the active energy ray-curable ink discharged from the droplet discharge head with active energy rays;
  An image forming apparatus comprising: a second irradiation unit that is disposed behind the recording head in the return path direction and irradiates the active energy ray-curable ink discharged from the droplet discharge head with active energy rays.
  The dot pattern data indicating a dot pattern formed by droplets discharged from the droplet discharge head is divided into partial dot pattern data indicating a plurality of partial dot patterns that are a part of the dot pattern, and An order determining unit that determines the order of forming the partial dot patterns;
  For each partial dot pattern, the formation of the partial dot pattern is assigned to the plurality of first nozzles or the plurality of second nozzles, and is finally formed at least in a unit region that is a unit for image formation. The formation of the partial dot pattern functions as an assignment determination unit assigned to the plurality of second nozzles,
  When the recording head moves in the main scanning direction to the plurality of second nozzles that eject the active energy ray curable ink having a glossiness of a threshold value or less, the active energy ray curable ink is Eject it onto the recording medium,
  When the recording head moves in the main scanning direction to the plurality of second nozzles that discharge the active energy ray curable ink having a color whose glossiness is greater than a threshold, the active energy ray curable ink is Discharging to a recording medium,
  program.   A recording head that moves in the main scanning direction on the recording medium;
  Mounted on the recording head, when the recording head moves in the forward path in the main scanning direction, and when the recording head moves in the backward path in the main scanning direction, the active energy ray-curable ink of a predetermined color is recorded in the recording head. When the recording head moves in one direction of either the forward path or the backward path in the main scanning direction, the active energy ray-curable ink having the same color as the predetermined color is recorded on the recording medium. A plurality of second nozzles for discharging to the liquid droplet discharge head;
  A first irradiation unit disposed behind the recording head in the forward direction and irradiating the active energy ray-curable ink discharged from the droplet discharge head with active energy rays;
  An image forming apparatus comprising: a second irradiation unit that is disposed behind the recording head in the return path direction and irradiates the active energy ray-curable ink discharged from the droplet discharge head with active energy rays.
  The dot pattern data indicating a dot pattern formed by droplets discharged from the droplet discharge head is divided into partial dot pattern data indicating a plurality of partial dot patterns that are a part of the dot pattern, and An order determining unit that determines the order of forming the partial dot patterns;
  For each partial dot pattern, the formation of the partial dot pattern is assigned to the plurality of first nozzles or the plurality of second nozzles, and is finally formed at least in a unit region that is a unit for image formation. The partial dot pattern is formed by an allocation determining unit that is allocated to the plurality of second nozzles;
  Program to function as.

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