JP5237060B2 - Inkjet recording method and apparatus - Google Patents

Description

  The present invention relates to an ink jet recording method and apparatus, and more particularly to an ink jet recording method and apparatus for recording an image by applying ink droplets to a recording medium after applying a treatment liquid having a function of aggregating ink coloring materials to a recording medium. .

  In an inkjet recording apparatus, when an image is recorded on plain paper (non-coated paper), there is a problem that bleeding occurs and a good image cannot be obtained.

In Patent Document 1, as a technique for preventing this bleeding, a treatment liquid having a function of aggregating ink color materials on paper is applied in advance, and ink droplets are ejected onto the paper to which the treatment liquid is applied, A method for recording an image has been proposed. Patent Document 1 proposes a method in which a processing liquid is applied to a sheet by bringing a roller to which the processing liquid is applied into contact with a sheet that is continuously conveyed at a constant speed.
JP 2005-225065 A

  By the way, the recording system of the inkjet recording apparatus includes a serial system in which the recording head performs recording while reciprocating (shuttle motion) in a direction orthogonal to the paper transport direction, and a full line system in which recording is performed without moving the recording head. There is. In the serial method, the sheet is intermittently conveyed during recording, and an image is recorded.

  For this reason, when an image is recorded by applying a treatment liquid as in Patent Document 1 with a serial type ink jet recording apparatus, there is a difference in time from application of the treatment liquid to ink droplet ejection depending on the location. (The time from the application of the treatment liquid to the time when ink droplets are ejected becomes longer toward the rear edge of the paper), and there is a difference in the penetration amount of the treatment liquid during ink ejection (after the paper) The amount of penetration of the treatment liquid increases toward the end).

  In addition, in a serial type inkjet recording apparatus, paper feeding is performed without performing main scanning in an area where an image is not recorded. Therefore, depending on the image to be recorded, ink droplets are ejected after the treatment liquid is applied depending on the location. A difference occurs in the time until the ink is discharged, and a difference occurs in the permeation amount of the treatment liquid at the time of ink ejection.

  Then, when a difference occurs in the permeation amount of the treatment liquid at the time of ink droplet ejection as described above, the fixing dot diameter varies, and as a result, density unevenness occurs.

  The present invention has been made in view of such circumstances, and reduces the occurrence of density unevenness due to variations in time from the application of the treatment liquid to the time when ink droplets are ejected. An object is to provide an ink jet recording method and apparatus capable of recording.

The invention according to claim 1, in order to achieve the above object, continuously conveying the recording medium at a constant speed, the treatment liquid for aggregating the coloring material of the ink to the entire area of the preset application area on the recording medium In the ink jet recording method for recording an image by intermittently transporting the recording medium and applying ink droplets onto the recording medium with a serial type recording head, determine the amount of penetration of the treatment liquid, the so ink droplets droplet ejection by the recording head reaches a predetermined fixing dot diameter, by correcting the ink volume in accordance with the amount of penetration was determined, hitting an ink droplet An ink jet recording method is provided.

  According to the present invention, when the recording medium is continuously conveyed to apply the treatment liquid and then the recording medium is intermittently conveyed to eject ink droplets, the amount of penetration of the processing liquid into the recording medium at the time of ink ejection The ink droplet ejection amount is corrected according to the obtained penetration amount. That is, since the fixing dot diameter changes according to the penetration amount (the fixing dot diameter increases as the penetration amount increases), the ink droplet ejection amount according to the penetration amount so that the fixing dot diameter becomes uniform. Correct. Thereby, the fixing dot diameter can be made uniform over the entire surface of the recording medium, and the occurrence of density unevenness can be prevented.

  In order to achieve the above object, the invention according to claim 2 obtains the time from the application of the treatment liquid to the start of main scanning by the recording head, and from each obtained width region to the main scanning. The ink jet recording method according to claim 1, wherein the penetration amount is obtained.

  According to the present invention, the time from when the treatment liquid is applied to when the main scanning by the recording head is started is obtained, and the permeation amount is obtained for each width region subjected to the main scanning from the obtained time. Since the amount of penetration into the recording medium depends on the elapsed time since the treatment liquid was applied, the time from the application of the treatment liquid to the start of the main scanning by the recording head is obtained, and the amount of penetration is determined from the obtained time. By determining, the amount of penetration of the processing liquid can be determined easily and accurately.

According to a third aspect of the present invention, in order to achieve the above object, the ink droplets ejected by the recording head based on the relationship between the amount of penetration of the processing liquid into the recording medium and the fixed dot diameter determined in advance are predetermined. The ink jet recording method according to claim 1, wherein the ink droplet ejection amount is corrected so as to obtain a fixed dot diameter.

  According to the present invention, the droplet ejection amount is corrected based on the relationship between the infiltration amount of the processing liquid into the recording medium and the fixed dot diameter determined in advance so that the ejected ink droplet has a predetermined fixing dot diameter. Is done. Thereby, the fixing dot diameter can be made uniform over the entire surface of the recording medium, and the occurrence of density unevenness can be prevented.

According to a fourth aspect of the present invention, in order to achieve the above object, a continuous conveying means for continuously conveying a recording medium at a constant speed, and an ink coloring material are aggregated on the recording medium continuously conveyed by the continuous conveying means. A treatment liquid application means for applying the treatment liquid to be applied; an intermittent conveyance means for intermittently conveying the recording medium to which the treatment liquid has been applied to the entire coating region set in advance; and a recording medium intermittently conveyed by the intermittent conveyance means An ink droplet ejecting means for ejecting ink droplets with a serial type recording head and an amount of penetration of the treatment liquid into the recording medium at the time of ink droplet ejection are obtained. An ink jet recording apparatus comprising: a droplet ejection amount correcting unit that corrects an ink ejection amount in accordance with the obtained penetration amount so as to obtain a fixed dot diameter .

  According to the present invention, in an ink jet recording apparatus that continuously conveys a recording medium and applies a treatment liquid, and then intermittently conveys the recording medium and ejects ink droplets, the treatment liquid applied to the recording medium at the time of ink ejection The permeation amount is obtained, and the ink droplet ejection amount is corrected according to the obtained permeation amount. Thereby, the fixing dot diameter can be made uniform over the entire surface of the recording medium, and the occurrence of density unevenness can be prevented.

  According to a fifth aspect of the present invention, in order to achieve the object, the droplet ejection amount correcting means obtains and obtains a time from when the treatment liquid is applied to when main scanning by the recording head is started. 5. The ink jet recording apparatus according to claim 4, wherein the permeation amount is obtained for each width region to be main scanned from time.

  According to the present invention, the time from when the treatment liquid is applied to when the main scanning by the recording head is started is obtained, and the permeation amount is obtained for each width region subjected to the main scanning from the obtained time. Thereby, the penetration amount of the treatment liquid can be obtained easily and accurately.

According to a sixth aspect of the present invention, in order to achieve the above object, the droplet ejection amount correcting means is configured to use the recording head based on the relationship between the amount of treatment liquid penetrating into the recording medium and the fixed dot diameter. 6. The ink jet recording apparatus according to claim 4, wherein the ink droplet ejection amount is corrected so that the ink droplets ejected in step 1 have a predetermined fixing dot diameter.

  According to the present invention, the droplet ejection amount is corrected based on the relationship between the infiltration amount of the processing liquid into the recording medium and the fixed dot diameter determined in advance so that the ejected ink droplet has a predetermined fixing dot diameter. Is done. Thereby, the fixing dot diameter can be made uniform over the entire surface of the recording medium, and the occurrence of density unevenness can be prevented.

  According to the present invention, it is possible to reduce the occurrence of density unevenness due to the variation in time from application of the treatment liquid to ink droplet ejection, and a good image can be recorded.

  Hereinafter, preferred embodiments of an ink jet recording method and apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

[Device configuration]
FIG. 1 is a cross-sectional view showing a schematic configuration of an embodiment of an ink jet recording apparatus to which the present invention is applied.

  The ink jet recording apparatus 10 is a serial type ink jet recording apparatus capable of recording an image by previously applying a processing liquid having a function of aggregating ink color material on the surface of the paper. A paper feeding unit 20 that performs processing liquid coating unit 30 that applies a processing liquid having a function of aggregating ink color material onto paper 12 fed from paper feeding unit 20, and paper 12 coated with the processing liquid. An ink ejection unit 70 that ejects ink droplets to record an image and a paper ejection unit 90 that ejects the paper 12 on which the image is recorded are configured.

  The paper feed unit 20 includes a paper feed cassette 22 in which the paper 12 cut to a specified size is set, and a feed roller 24 that feeds the paper 12 set in the paper feed cassette 22. .

  The paper feed cassette 22 is formed in a rectangular box shape, and is detachably attached to the apparatus main body 10A. The paper 12 is stacked and set in the paper feed cassette 22 with the image recording surface facing downward.

  The feed roller 24 is disposed above the paper feed cassette 22 set at a predetermined position. The feeding roller 24 is formed in a half moon shape and is driven to rotate by a motor (not shown). The paper 12 set in the paper feed cassette 22 is fed one by one toward the processing liquid coating unit 30 in order from the top as the feed roller 24 rotates.

  The sheet 12 fed from the sheet feeding unit 20 travels on a conveyance path 26 formed in an arc shape, and a processing liquid is applied by a processing liquid application unit 30 provided in the middle thereof.

  The treatment liquid application unit 30 applies a liquid (treatment liquid) in which a treatment agent (aggregation accelerator) having a function of aggregating the color material by reacting with ink is dissolved to the surface of the paper 12 (image recording surface). . As shown in FIG. 2, the processing liquid application unit 30 includes a backup roller 32 that supports the paper 12, an application roller 34 that applies the processing liquid to the paper 12, and a processing liquid supply that supplies the processing liquid to the application roller 34. A unit 36 and a tip detection sensor 38 that detects the tip of the paper 12 are provided.

  The backup roller 32 and the application roller 34 are arranged to face each other with the conveyance path 26 of the paper 12 interposed therebetween. The backup roller 32 and the application roller 34 are formed with substantially the same length, and are longer than the width of the paper 12. The sheet 12 is conveyed while being sandwiched between the backup roller 32 and the application roller 34. Then, the processing liquid supplied to the surface (outer peripheral surface) of the application roller 34 is transferred during the conveyance process, and the processing liquid is applied to the image recording surface.

  The backup roller 32 is attached to a backup roller support frame (not shown). Both ends of the backup roller 32 are pivotally supported by a bearing provided on the backup roller support frame and are rotatably supported. The backup roller support frame is provided so as to be movable forward and backward with a predetermined movement stroke with respect to the application roller 34 and is urged toward the application roller 34 by an urging means (not shown) (for example, a spring). .

  Further, the backup roller 32 is subjected to a liquid repellent treatment on its surface (outer peripheral surface) (for example, coating with Teflon (registered trademark)) so that the treatment liquid is difficult to adhere.

  The application roller 34 is attached to an application roller support frame support frame (not shown). Both ends of the application roller 34 are pivotally supported by a bearing provided on the application roller support frame, and the application roller 34 is rotatably supported. The coating roller support frame is provided so as to be able to move forward and backward with respect to the backup roller 32, and can be moved between a predetermined contact position and a standby position by being driven by an actuator (not shown) such as a cylinder. Is provided. The application roller 34 is pressed against the surface of the backup roller 32 when the application roller support frame moves to the contact position, and is separated from the backup roller 32 when moved to the standby position.

  Further, a motor (not shown) is mounted on the coating roller support frame, and the coating roller 34 is driven to rotate by the motor. The paper 12 is transported along the transport path 26 as the application roller 34 rotates.

  The processing liquid supply unit 36 supplies the processing liquid to the surface (outer peripheral surface) of the application roller 34 with a predetermined thickness. The processing liquid supply unit 36 processes the processing liquid holding block 40 that holds the processing liquid with the coating roller 34, the processing liquid tank 42 that stores the processing liquid, and the processing liquid tank 42 to the processing liquid holding block 40. A treatment liquid supply pump 44 for feeding the liquid is provided.

  As shown in FIG. 3, the treatment liquid holding block 40 is formed in a rectangular plate shape having a width (length in the longitudinal direction) substantially the same as the width (length in the axial direction) of the application roller 34. It is provided in parallel with the axis of the roller 34. On the back surface (surface facing the application roller 34) of the processing liquid holding block 40, a recess 46 having a circular cross section is formed. An annular contact member 48 is attached so as to surround the edge of the recess 46.

  The contact member 48 is formed so as to protrude from the back surface of the treatment liquid holding block 40 by a predetermined amount, and is formed so as to be in close contact with the outer peripheral surface of the application roller 34. The treatment liquid holding block 40 is pressed and brought into contact with the outer peripheral surface of the application roller 34 through the contact member 48.

  The processing liquid holding block 40 is pressed and brought into contact with the outer peripheral surface of the application roller 34 via the contact member 48, thereby forming a liquid-tight space 50 between the outer periphery of the application roller 34. That is, when the contact member 48 is pressed and brought into contact with the outer peripheral surface of the application roller 34, the recess 46 formed on the back surface of the treatment liquid holding block 40 is covered with the application roller 34, thereby forming a liquid-tight space 50. Is done.

  A treatment liquid is supplied to the space 50, and the treatment liquid supplied to the space 50 is supplied to the application roller 34. That is, when the processing liquid is supplied to the space 50, the processing liquid is held on the outer peripheral surface of the application roller 34. Therefore, when the application roller 34 is rotated in this state, the outer peripheral surface of the application roller 34 continuously contacts the processing liquid. As a result, the processing liquid is continuously supplied to the outer peripheral surface of the application roller 34 with a predetermined thickness.

  On the surface of the processing liquid holding block 40, a processing liquid supply port 52 </ b> A and a processing liquid recovery port 52 </ b> B that are communicated with the recess 46 that forms the space 50 are formed.

  A processing liquid supply pipe 54 is connected to the processing liquid supply port 52 </ b> A, and the processing liquid supply pipe 54 is connected to the processing liquid tank 42 via a processing liquid supply pump 44. The processing liquid stored in the processing liquid tank 42 is sent to the processing liquid supply pump 44 and supplied to the space 50.

  On the other hand, a processing liquid recovery pipe 56 is connected to the processing liquid recovery port 52 </ b> B, and the processing liquid recovery pipe 56 is connected to the processing liquid tank 42 via a valve 58. The processing liquid supplied to the space 50 is held in the space 50 by closing the valve 58, and is collected in the processing liquid tank 42 by opening.

  The treatment liquid holding block 40 is attached to a frame that supports the application roller 34 and is supported so as to be movable forward and backward with respect to the application roller 34. And it is urged | biased by the spring 60 interposed between the frames, and is pressed with the predetermined pressing force on the outer peripheral surface of the application roller 34.

  The treatment liquid application unit 30 is configured as described above, and the paper 12 is conveyed through the treatment liquid application unit 30 while being sandwiched between the backup roller 32 and the application roller 34. Then, the processing liquid supplied to the surface of the application roller 34 is transferred during the conveyance process, and the processing liquid is applied to the image recording surface.

  The application roller 34 is driven according to the passage timing of the paper 12. That is, the application roller 34 is normally located at the standby position, and the sheet 12 is applied to the application position (the position where the application roller 34 moved to the contact position contacts the backup roller 32: the processing liquid is applied at this position. When the sheet is conveyed to the contact position, the processing liquid is applied to the sheet 12. More specifically, when the front end of the application region (region where the processing liquid is applied) set on the paper 12 is transported to the application position, it is moved to the application position accordingly, and the rear end of the application region Is transferred to the application position, it is moved to the standby position. As a result, the treatment liquid can be applied only to a prescribed region. This also prevents the treatment liquid from adhering to the backup roller 32.

  The rotation of the application roller 34 is continuously performed at a constant rotation speed. Accordingly, the paper 12 is continuously fed at a constant speed, and the processing liquid is continuously applied.

  The application area is set wider than a recording area (an area where an ink droplet is landed to record an image) in order to ensure a reaction by the treatment liquid. The width of the application region is defined by the supply width of the processing liquid supplied to the application roller 34, and the supply width of the processing liquid supplied to the application roller 34 is the width of the space 50 formed by the processing liquid supply unit 36 (= Width of the recess 46).

  The leading edge detection sensor 38 is installed immediately before the coating roller 34 and detects the leading edge of the paper 12 introduced into the coating roller 34.

  The paper 12 on which the treatment liquid is applied by the treatment liquid application unit 30 as described above is conveyed to the ink droplet ejection unit 70, and ink droplets are ejected onto the surface thereof to record an image.

  As shown in FIG. 1, the ink droplet ejection unit 70 includes a platen 72, a first conveyance roller pair 74, a second conveyance roller pair 76, an ink droplet ejection unit 78, and a tip detection sensor 80. ing.

  The platen 72 is installed horizontally. The sheet 12 conveyed through the arcuate conveyance path 26 is placed on the platen 72.

  The first transport roller pair 74 and the second transport roller pair 76 transport the paper 12 placed on the platen 72.

  The first transport roller pair 74 is installed at the upstream side of the platen 72 in the transport direction. The first conveying roller pair 74 includes a driving roller 74A and a driven roller 74B. The driving roller 74A and the driven roller 74B are arranged to face each other with the platen 72 interposed therebetween, and both ends thereof are rotatably supported by bearings (not shown) provided in the apparatus main body 10A. A motor (not shown) is connected to the drive roller 74A and is driven to rotate by the motor. The sheet 12 conveyed through the arc-shaped conveyance path 26 is placed on the platen 72 and is supplied between the driving roller 74A and the driven roller 74B of the first conveyance roller pair 74. Then, the sheet is sandwiched between the driving roller 74A and the driven roller 74B of the first conveying roller pair 74 and conveyed on the platen 72.

  The second conveyance roller pair 76 is installed at the downstream side of the platen 72 in the conveyance direction. The second conveying roller pair 76 includes a driving roller 76A and a driven roller 76B. The driving roller 76A and the driven roller 76B are disposed to face each other with the platen 72 interposed therebetween, and both ends thereof are rotatably supported by bearings (not shown) provided in the apparatus main body 10A. A motor (not shown) is connected to the drive roller 76A, and is driven to rotate by the motor. The sheet 12 conveyed on the platen 72 is supplied between the driving roller 76A and the driven roller 76B of the second conveying roller pair 76. Then, the sheet is sandwiched between the driving roller 76A and the driven roller 76B of the second conveying roller pair 76 and conveyed toward the paper discharge unit 90 at the subsequent stage.

  The ink droplet ejection unit 78 ejects four color ink droplets of C, M, Y, and K onto the paper 12 conveyed on the platen 72 and records a color image on the paper 12. As shown in FIG. 4, the ink droplet ejection unit 78 includes a recording head 82 and a carriage 84 that reciprocally moves the recording head 82 in a direction (main scanning direction) orthogonal to the conveyance direction (sub-scanning direction) of the paper 12. And is configured.

  The carriage 84 is slidably supported by two guide shafts 86 disposed in a direction perpendicular to the conveyance direction of the paper 12, and is guided by the two guide shafts 86 to move in the main scanning direction. It is provided freely. Then, it is driven by a driving means (not shown) and reciprocates in the main scanning direction.

  The recording head 82 has a discharge surface formed on a surface (lower surface) facing the paper 12, a nozzle for discharging Y ink droplets on the discharge surface, and a nozzle for discharging C ink droplets. A plurality of nozzles for ejecting M ink droplets and a plurality of nozzles for ejecting K ink droplets are formed in parallel for each color.

  The method for arranging the nozzles is not particularly limited, and the nozzles may be arranged in a line for each color in a direction orthogonal to the main scanning direction, or may be arranged in a staggered manner.

  Each nozzle is provided with energy generating means for generating energy for ejecting ink droplets. The recording head 82 applies the energy generated from the energy generating means to the ink in the nozzle, and ejects ink droplets individually from each nozzle.

  As the energy generating means, an electromechanical transducer element such as a piezo element, an electrothermal transducer element such as a heating resistor, an electromagnetic mechanical converter element that converts electromagnetic waves such as radio waves and lasers into mechanical vibrations or heat, An electromagnetic wave heat transducer element or the like can be used.

  Further, an ink cartridge (not shown) is mounted on the carriage 84, and ink is supplied from this ink cartridge to the nozzles (so-called on-carriage method). The ink cartridge is mounted for each color of Y, C, M, and K, and ink is supplied from the ink cartridge of the corresponding color to each nozzle.

  The ink cartridge may be installed in another place without being mounted on the carriage, and the ink may be supplied by connecting the recording head on the carriage with a tube (so-called off-carriage method).

  The leading edge detection sensor 80 is installed at a position immediately before the recording head 82 and detects the leading edge of the paper 12 introduced into the recording head 82.

  The ink ejection unit 70 configured as described above selectively ejects ink droplets from each nozzle while reciprocating the recording head 82 with respect to the paper 12 conveyed on the platen. Record a color image on

  The main scanning of the recording head 82 is performed in a state where the paper 12 is stopped, and the paper 12 is conveyed by a predetermined feed amount in the sub-scanning direction every time the recording head 82 is main-scanned once. . Image recording is performed by repeating main scanning by the recording head 82 and feeding of the paper 12 in the sub-scanning direction. Therefore, the sheet 12 is intermittently conveyed during image recording.

  Here, as described above, the application of the treatment liquid is performed by continuously conveying the paper 12. Accordingly, after the processing liquid is applied by the processing liquid application unit 30, the conveyance method of the paper 12 is switched to intermittent conveyance. In order to enable switching of the transport method, the center-to-center distance L1 between the coating roller 34 and the recording head 82 is designed to be longer than the length L0 of the paper 12. Thereby, after the paper 12 is continuously conveyed by the treatment liquid application unit 30 and the treatment liquid is applied, the paper 12 is intermittently conveyed by the ink droplet ejection unit 70 and an image can be recorded.

  Note that the feed amount of the paper 12 at the time of image recording is set corresponding to the width of the image (main scanning width) recorded by one main scanning of the recording head 82.

  Further, the image recording is performed in each of the forward path and the backward path of the recording head 82. That is, ink droplets are ejected not only in the forward path of the recording head 82 but also in the backward path, and an image is recorded. In this case, the paper 12 is sub-scan fed after each main scanning in the forward path and the backward path.

  If there is no image to be recorded in the main scanned area, the main scanning is not performed in the area, and the paper 12 is sub-scanned to the area where the image to be recorded is present.

  In this example, an image is recorded with four colors of inks of C, M, Y, and K. However, the combination of ink colors and the number of colors to be used is not limited to this. You may add and use light ink, dark ink, special color ink, etc. as needed. For example, a configuration in which an ink jet head that discharges light ink such as light cyan and light magenta is added is also possible. Also, the arrangement order of the ink jet heads for each color is not particularly limited.

  As the composition of the ink, an ink containing a pigment as a colorant, a resin polymer, a dispersant, a surfactant, or the like is used.

  The paper discharge unit 90 includes a paper discharge tray 92. The sheet 12 on which the image is recorded by the ink droplet ejection unit 70 is conveyed to the second conveyance roller pair 76 of the ink droplet ejection unit 70 and is discharged to the paper discharge tray 92.

  FIG. 5 is a block diagram illustrating a schematic configuration of a control system of the ink jet recording apparatus according to the present embodiment.

  As shown in the figure, the inkjet recording apparatus 10 includes a communication interface 110, a system controller 112, an image memory 114, an image processing unit 116, a paper feed control unit 118, a processing liquid application control unit 120, an ink droplet ejection control unit 122, and the like. It has.

  The communication interface 110 is an interface unit that receives image data sent from the host computer 100. Image data sent from the host computer 100 is taken into the inkjet recording apparatus 10 via the communication interface 110.

  The system controller 112 is a control unit that controls each unit of the inkjet recording apparatus 10 and includes a CPU, a ROM, a RAM, and the like. The system controller 112 controls each part of the inkjet recording apparatus 10 according to a predetermined control program. The ROM stores a control program executed by the system controller 112 and various data necessary for control.

  The image memory 114 is a storage unit that temporarily stores image data input via the communication interface 110, and data is read and written through the system controller 112.

  The image processing unit 116 generates a print control signal (dot data) from the image data in response to a command from the system controller 112.

  The paper feed control unit 118 controls driving of the paper feed unit 20 in accordance with a command from the system controller 112. That is, driving of a motor connected to the feeding roller 24 is controlled, and feeding of the paper 12 set in the paper feeding cassette 22 is controlled.

  The treatment liquid application control unit 120 controls driving of the treatment liquid application unit 30 in accordance with a command from the system controller 112. That is, the driving of the motor connected to the application roller 34 is controlled to control the supply of the processing liquid to the application roller 34 and the movement of the frame that supports the application roller 34 is controlled to process the paper 12. Control the application of liquid. Further, the supply of the processing liquid to the space 50 and the recovery thereof are controlled by controlling the driving of the processing liquid supply pump 44 and the valve 58.

  The ink droplet ejection control unit 122 controls driving of the ink droplet ejection unit 70 in accordance with an instruction from the system controller 112. In other words, the driving of the motors connected to the first conveying roller pair 74 and the second conveying roller pair 76 is controlled to control the conveyance of the paper 12, and the recording head 82 provided in the ink droplet ejection unit 78 is driven. And a predetermined image is recorded on the paper 12. Specifically, a signal for driving the recording head 82 is generated based on the dot data given from the system controller 112, and the generated driving signal is supplied to the recording head 82. Thereby, the ejection amount (droplet ejection amount) and ejection timing of each color ink droplet ejected from the recording head 82 are controlled.

[Image recording operation]
Next, an image recording operation by the inkjet recording apparatus 10 of the present embodiment will be described.

  As described above, in the ink jet recording apparatus 10 of the present embodiment, the processing liquid that aggregates the color material of the ink is applied to the surface of the paper in advance to record an image.

  Image recording is performed in response to a print instruction from the host computer. When a print instruction from the host computer and an image to be printed are received, dot data is generated from the image data to be printed and the image is recorded. Start processing.

  The paper 12 set in the paper feed cassette 22 is fed to the processing liquid coating unit 30 by the feeding roller 24, and the processing liquid is coated on the surface (image recording surface).

  The treatment liquid is applied by the application roller 34, and the treatment liquid is applied to the surface of the paper 12 with a certain thickness by pressing the application roller 34 supplied with the treatment liquid to the surface of the paper 12. Is done.

  The application roller 34 stands by while rotating at the standby position until the tip of the application region of the paper 12 reaches a predetermined application position. When the tip of the application area of the paper 12 reaches the application position, it moves to the contact position and is pressed against the surface of the paper 12 while rotating.

  The application roller 34 stands by while rotating, whereby the processing liquid is continuously supplied from the processing liquid supply unit 36 to the surface thereof.

  In addition, the processing liquid is transferred from the application roller 34 to the surface of the paper 12 while the rotating application roller 34 is pressed and brought into contact with the surface of the sheet 12 while being conveyed at a constant speed. The treatment liquid is continuously applied.

  The paper 12 coated with the treatment liquid is transported to the ink droplet ejection unit 70, and ink droplets of each color of C, M, Y, and K are deposited on the surface coated with the treatment liquid, and an image is recorded. .

  The ink droplets are ejected by the recording head 82, and the main scanning of the recording head 82 and the feeding of the paper 12 in the sub-scanning direction are repeated to record an image on the image recording area of the paper 12.

  The sheet 12 on which the image is recorded is conveyed on the platen and discharged onto the sheet discharge tray 92.

  An image is recorded on the surface of the paper 12 by a series of operations as described above.

[Relationship between treatment liquid penetration and fixing dot diameter]
As described above, in the ink jet recording apparatus 10 of the present embodiment, ink droplets are ejected by previously applying a treatment liquid that agglomerates ink color material onto paper.

  Here, the treatment liquid is applied by the application roller 34, and the paper 12 is continuously conveyed to apply the treatment liquid.

  On the other hand, ink droplets are ejected by the serial type recording head 82, and the paper 12 is intermittently transported to eject ink droplets.

  FIG. 6 is a diagram illustrating a change in the paper transport method. As shown in the figure, the first image recording area of the paper 12 (the area that is first scanned by the recording head 82) is the ink droplet ejection position (the ink droplets ejected from the nozzles of the recording head 82). Is continuously conveyed until it reaches a position where droplets are ejected. When the first image recording area reaches the ink droplet ejection position, the image is recorded intermittently and thereafter recorded.

  Since the transport method of the paper 12 is switched between the application of the treatment liquid and the ink droplet ejection in this way, the center-to-center distance L1 between the coating roller 34 and the recording head 82 is in the transport direction of the paper 12. It is set to be longer than the length L0 (L1> L0).

  Now, after continuously transporting the paper 12 and applying the treatment liquid in this way, when the paper 12 is intermittently transported and ink droplets are ejected, the ink droplets are ejected after the treatment liquid is applied. Variation (time of droplet ejection start: T) occurs. That is, the droplet ejection start time T becomes longer toward the rear end in the transport direction of the paper 12.

  On the other hand, as shown in FIG. 7, the treatment liquid applied to the paper 12 increases in the amount of penetration into the paper as time passes. In the same figure, (a) shows a state in which the treatment liquid has just been applied to the paper 12 and almost no penetration into the inside of the paper has started, and (b) shows that a predetermined time has passed since the treatment liquid was applied. In the state where a part of the processing liquid has permeated the inside of the sheet, (c) shows a state in which almost all the processing liquid has permeated the inside of the sheet as time passes. As described above, the treatment liquid applied to the paper 12 increases in the amount of penetration into the paper as time passes.

  The applicant of the present application investigated the relationship between the penetration amount of the treatment liquid and the fixing dot diameter of the ejected ink droplet. As a result, it was confirmed that as the amount of the treatment liquid permeated increased, the tendency of insufficient aggregation occurred. That is, it was confirmed that the tendency of insufficient aggregation in the order of (a) → (b) → (c) in FIG.

  In consideration of this, in the state of FIG. 7A, that is, in a state where the treatment liquid is applied to the paper 12 and almost no penetration into the paper starts, the ink that has landed on the paper is applied to the surface of the paper. Since the reaction is started simultaneously with the landing of the existing processing solution, the lack of aggregation hardly occurs.

  On the other hand, in the state of FIG. 7C, that is, in a state where almost all of the processing liquid has permeated the inside of the paper, after the ink has landed on the paper, the processing liquid that has permeated the inside of the paper has landed on the paper surface again. It is presumed that a part of the processing liquid remaining in the permeation state does not contribute to the aggregation reaction and a tendency of insufficient aggregation occurs due to the aggregation reaction through the step of dissolving in the ink.

  When the aggregation is insufficient, it is confirmed that the fixing area of the aggregated color material in the ink droplet is increased and the dot diameter is visually recognized as large.

  FIG. 8A is a graph showing the relationship between the elapsed time from application (= droplet ejection start time T) and the amount of treatment liquid penetrating into the paper. As shown in the figure, the amount of the treatment liquid penetrating into the paper increases with the lapse of time since application.

  FIG. 8B is a graph showing the relationship between the penetration amount of the processing liquid into the paper and the fixing dot diameter. As shown in the figure, the fixing dot diameter increases as the amount of treatment liquid penetrating into the paper increases.

  FIG. 8C is a graph showing the relationship between the droplet ejection start time T and the fixing dot diameter. As shown in the figure, as the droplet ejection start time T (= elapsed time from application) becomes longer, the amount of the treatment liquid penetrating into the paper becomes larger, so that the fixed dot diameter becomes larger.

  By the way, when variations in the fixing dot diameter occur in one sheet 12 as described above, density unevenness (aggregation unevenness) occurs in the recorded image.

  In order to prevent such density unevenness, it is necessary to make the fixing dot diameter uniform. As shown in FIG. 8C, the fixing dot diameter changes in accordance with the amount of treatment liquid penetrating into the paper. Then, the penetration amount of the processing liquid into the sheet changes according to the droplet ejection start time T. Therefore, by adjusting the ink droplet ejection amount according to the droplet ejection start time T, the fixed dot diameter can be made uniform.

  FIG. 9 is a graph showing the relationship between the ink droplet ejection amount and the droplet ejection start time T for obtaining a predetermined fixing dot diameter.

  In general, the fixing dot diameter increases according to the amount of ink droplets ejected. That is, if the droplet ejection amount is increased, the fixing dot diameter is increased accordingly.

  On the other hand, as described above, even when droplets are ejected with the same droplet ejection amount, the fixed dot diameter increases as the droplet ejection start time T increases (see FIG. 8C).

  Therefore, by reducing the droplet ejection amount as the droplet ejection start time T becomes longer (= decreasing the droplet ejection amount as the droplet ejection start time T becomes shorter), the ink droplets ejected from the nozzles are fixed to a predetermined extent. The dot diameter can be set.

  The permeation characteristics and aggregation reactivity of the treatment liquid differ depending on the combination of ink used, treatment liquid, and paper (recording medium), but the droplet ejection start time shown in FIG. 9 in advance depends on the ink, treatment liquid, and paper used. The relationship between T and the ink droplet ejection amount is obtained by experiments, simulations, etc., and the ink droplet ejection amount according to the droplet ejection start time T from the relationship between the obtained droplet ejection start time T and the ink droplet ejection amount. By correcting this, it is possible to make the fixing dot diameter uniform over the entire sheet.

[Method of correcting ink drop amount]
As described above, the relationship between the droplet ejection start time T and the ink droplet ejection amount is obtained in advance according to the ink, processing liquid, and paper to be used, and the ink droplet ejection amount according to the droplet ejection start time T. By correcting this, it is possible to make the fixing dot diameter uniform over the entire sheet.

  The droplet ejection start time T is obtained for each width region main-scanned by the recording head 82, and the ink droplet ejection amount is corrected for each main-scan width region.

  Here, the droplet ejection start time T (n) for each main scanning width region S (n) of the recording head 82 is obtained as follows.

  The conveyance speed of the paper 12 in the continuous conveyance area is V1 [mm / s], the conveyance speed of the paper 12 in the intermittent conveyance area is V2 [mm / s], and the main scanning speed of the recording head 82 is V3 [mm / s]. The center distance between the coating roller 34 and the recording head 82 is L1 [mm], the sub-scan feed amount (= sub-scan width) of the paper 12 is L2 [mm], and the main scanning length of the recording head 82 is L3 [mm].

The droplet ejection start time T1 of the width region S1 to be main scanned first is
[Equation 1]
T1 = L1 / V1 [sec]
Is required.

Further, the droplet ejection start time T2 of the width region S2 to be main scanned next is
[Equation 2]
T2 = {(L1-1 × L2) / V1} + (L3 / V3) + (L2 / V2) [sec]
Is required.

  Here, (L1-1 × L2) / V1 is a continuous conveyance time, L3 / V3 is a main scanning time, and L2 / V2 is a sub-scanning time.

Further, the droplet ejection start time T3 of the width region S3 to be main scanned next is
[Equation 3]
T3 = {(L1-2 × L2) / V1} + 2 × (L3 / V3) + 2 × (L2 / V2) [sec]
Is required.

That is, the droplet ejection start time T (n) in each main scanning width region S (n) is
[Equation 4]
T (n) = [{L1− (n−1) × L2} / V1] + (n−1) × (L3 / V3) + (n−1) × (L2 / V2) [sec]
Can be obtained.

  Note that the above calculation method is a case where an image exists in all width regions to be main scanned.

  However, as shown in FIG. 10, when there is a width area (S4, S5) in which there is no image to be recorded in the width area to be main scanned, the width area (S4, S5) is not main scanned. Skipped to In this case, the droplet ejection start time T (n) of each width region S (n) is calculated as follows.

In the example shown in FIG. 10, since the image does not exist in the fourth and fifth width areas S4 and S5, the sheet 12 is sub-scanned at a stretch to the sixth width area S6 after the third main scan. Sent. In this case, the droplet ejection start time T (n) in the first to third width regions is
[Equation 5]
T (n) = [{L1− (n−1) × L2} / V1] + (n−1) × (L3 / V3) + (n−1) × (L2 / V2) [sec]
Can be obtained.

That is, the droplet ejection start time T1 of the width region S1 to be main scanned first is
[Equation 6]
T1 = L1 / V1 [sec]
The droplet ejection start time T2 of the width region S2 to be second main scanned is
[Equation 7]
T2 = {(L1-1 × L2) / V1} + (L3 / V3) + (L2 / V2) [sec]
The droplet ejection start time T3 of the width region S3 to be main scanned third is:
[Equation 8]
T3 = {(L1-2 × L2) / V1} + 2 × (L3 / V3) + 2 × (L2 / V2) [sec]
Is required.

  Since the fourth and fifth width regions S4 and S5 are not subjected to main scanning, the paper 12 is sub-scan fed to the sixth width region S6 all at once.

The droplet ejection start time T6 in the sixth width region S6 is
[Equation 9]
T6 = {(L1-5 × L2) / V1} + 3 × (L3 / V3) +5 (L2 / V2) [sec]
Can be obtained. That is, the droplet ejection start time is shortened by the amount that the width regions S4 and S5 are not main-scanned.

  As described above, when an image is recorded while skipping a part of the main scanning width region, the droplet ejection start time T (in the main scanning width region S (n) is considered in consideration of the skipped region. By calculating n), the droplet ejection start time T (n) of the width region S (n) of each main scan can be appropriately obtained.

  As described above, the droplet ejection start time T (n) of each main scanning width region S (n) can be obtained by calculation according to the presence or absence of the width region to be skipped. The presence or absence of the main scanning width area to be skipped is determined according to the image to be recorded. That is, the main scanning width region without an image is skipped.

  Normally, the main scanning width area without an image is skipped for shortening the printing time, but main scanning can be performed without ejecting ink droplets. In this case, the paper 12 is sub-scan fed at a constant speed in the entire main scanning width region.

  The droplet ejection start time T (n) of each width region S (n) can be obtained as described above.

  On the other hand, the relationship between the droplet ejection start time T and the ink droplet ejection amount (see FIG. 9) varies depending on the combination of ink, processing liquid, paper (recording medium), etc. used. The relationship with the amount is obtained in advance by experiments, simulations, etc. according to the ink, processing liquid, paper, etc. to be used. Then, the obtained relationship is tabulated or converted into a function and stored in a memory (in this example, stored in the ROM of the system controller 112).

  Specifically, the relationship between the droplet ejection start time and the penetration amount, the relationship between the penetration amount and the fixing dot diameter, and ink ejection for obtaining a predetermined fixing dot diameter (target fixing dot diameter) with respect to the fixing dot diameter. The drop amount relationship is obtained in advance by experiments, simulations, etc. according to the ink, processing liquid, paper, etc. to be used, and each relationship is made into a table or a function and stored in a memory.

  At the time of image recording, ink droplet ejection is performed by referring to a table stored in the memory or using a function to set the ink ejection amount of each width region S (n).

  Note that the droplet ejection start time T (n) in each main scanning width region S (n) can also be tabulated. In particular, when ink droplets are ejected without skipping the entire main scanning width region, the droplet ejection start time T (n) in each main scanning width region S (n) is uniformly determined, and is therefore tabulated. It is effective.

  In this example, the droplet ejection start time T (n) of each main scanning width region S (n) when ink droplets are ejected without skipping the entire main scanning width region is tabulated and stored in the memory. Stored (stored in the ROM of the system controller 112). Therefore, when ink droplets are ejected without skipping the entire main scanning width region, the droplet ejection start time T (n) of each main scanning width region S (n) is obtained with reference to this table. It is done.

  On the other hand, when there is a width region to be skipped, the droplet ejection start time T (n) of each width region S (n) for main scanning is obtained by calculation.

  FIG. 11 is a flowchart showing a procedure for setting the ink droplet ejection amount in the width region S (n) of each main scan.

  n is the number of the width region of main scanning, and N is the number of the final width region (N = 10 in the example shown in FIG. 10).

  First, n is set to 1 (step S10), and it is determined whether or not to skip a main scanning width area without an image (step S11). If the image is present in the entire main scanning width region of the recording target image, or if the recording target image has a main scanning width region without an image, recording is performed without skipping, “No”. On the other hand, if the recording target image has a main scanning width area without an image and the width area is skipped, “Yes” is set.

  When recording without skipping (in the case of “No”), the droplet ejection start time T (n) of the target main scanning width region is read from the table stored in the ROM (step S12). That is, the droplet ejection start time T (n) of the nth width region S (n) is read from the table stored in the ROM. For example, in the case of the first width region S1, the droplet ejection start time T1 of the first width region S1 is read from a table stored in the ROM.

  On the other hand, when recording is performed while skipping the main scan without an image (in the case of “Yes”), the droplet ejection start time T (n) of the width region of the target main scan is calculated in consideration of the width region to be skipped. ) Is calculated (step S13). That is, the calculation is performed in consideration of a region where the droplet ejection start time T (n) of the nth width region S (n) is skipped. For example, as shown in FIG. 10, when the fourth and fifth width regions S4 and S5 are skipped and the droplet ejection start time T6 of the sixth width region S6 is obtained, the skip is performed. The droplet ejection start time T6 of the sixth width region S is calculated in consideration of the width regions S4 and S5 to be performed.

  In this way, the droplet ejection start time T (n) of the target width region S (n) is obtained according to the presence or absence of skipping.

  Then, the permeation amount P (n) of the processing liquid corresponding to the obtained droplet ejection start time T (n) is read from the table stored in the ROM, and the permeation amount P (n of the processing liquid in the target width region S (n). ) Is obtained (step S14).

  Further, the fixing dot diameter D (n) corresponding to the obtained penetration amount P (n) is read from the table stored in the ROM, and the fixing dot diameter D (n) of the target width region S (n) is obtained (step S15). ).

  Then, with respect to the determined fixing dot diameter D (n), the ink droplet ejection amount V (n) for obtaining the predetermined fixing dot diameter D is read from the table stored in the ROM, and the target width region S (n) The ink droplet ejection amount V (n) is obtained at step S16. That is, the initial ink droplet ejection amount (ink droplet ejection amount in each width region set by the dot data of the print target image) is corrected.

  As described above, the ink droplet ejection amount V (n) for one target width region S (n) is set. Thereafter, 1 is added to n (n = n + 1) (step S17), and it is determined whether or not the setting of the ink droplet ejection amount in the full width region is completed. That is, it is determined whether n exceeds N (n> N) (step S18).

  When n exceeds N, the setting of the ink droplet ejection amount for the entire width region is completed, and the processing is completed. On the other hand, if n does not exceed N, the setting of the ink droplet ejection amount for the full width region has not been completed, so the process returns to step S11 and the above processing is executed again to perform the ink droplet ejection amount for the target width region. Set.

  As described above, the ink droplet ejection amount V (n) in the width region S (n) of each main scan is set.

  The above arithmetic processing is executed by the system controller 112 according to a predetermined arithmetic program.

  Thereafter, the system controller 112 starts a recording process, and injects ink droplets with a set ink ejection amount in the width region of each main scan, and records an image.

  As described above, in the inkjet recording apparatus 10 according to the present embodiment, the ink droplet ejection amount is corrected so that a predetermined fixing dot diameter is obtained in consideration of the variation in the fixing dot diameter based on the variation in the droplet ejection start time. To record an image. Thereby, generation | occurrence | production of an aggregation nonuniformity can be suppressed and a high quality image can be recorded.

  In the above embodiment, the penetration amount of the processing liquid in the width region of each main scan is obtained from the droplet ejection start time. In addition, for example, a moisture meter is provided at the ink ejection position by the recording head 82. It may be installed, and the permeation amount of the treatment liquid in the width region of each main scan may be obtained from the detection result of the moisture meter.

  In the above embodiment, when there is no image in the main scanning width area, the area is skipped. However, even if there is no image in the main scanning width area, recording is not performed. You may make it do. In this case, the area is subjected to main scanning without performing ink droplet ejection.

  In addition, when an image is recorded without skipping in this way, there is an effect that it is not necessary to perform complicated calculation even when halftone processing by error diffusion is performed.

  In the above embodiment, the processing for generating dot data from the image data to be printed is performed by the dedicated image processing unit. However, the system controller 112 may perform processing by software.

  In the above embodiment, the dot data is generated by the ink jet recording apparatus. However, the dot data may be generated by the host computer and received by the ink jet recording apparatus.

  In the above embodiment, the treatment liquid is applied by the application roller and supplied to the paper, but the method for supplying the treatment liquid is not limited to this. In addition, for example, the treatment liquid may be ejected and supplied to the paper by the recording head in the same manner as the ink droplet ejection. In this case, it is preferable to supply with a full-line type recording head.

Cross-sectional view of inkjet recording apparatus Schematic configuration diagram of treatment liquid application part Bottom view of treatment liquid holding block Schematic configuration diagram of ink droplet ejection unit Block diagram of control system of ink jet recording apparatus Diagram showing transition of paper transport method Diagram showing process liquid penetration (A): a graph showing the relationship between the elapsed time from application and the amount of penetration of the treatment liquid into the paper; (b): a graph showing the relationship between the amount of penetration of the treatment liquid into the paper and the fixing dot diameter; (C): a graph showing the relationship between the droplet ejection start time T and the fixing dot diameter A graph showing the relationship between the ink droplet ejection amount and the droplet ejection start time T for obtaining a predetermined fixing dot diameter The figure which shows an example of the recording target image which does not have an image in a part of width area scanned by main scanning Flow chart showing the procedure for setting the ink ejection amount

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device, 12 ... Paper, 20 ... Paper feed part, 30 ... Treatment liquid application part, 34 ... Application roller, 36 ... Application roller, 70 ... Ink drop part, 78 ... Ink drop unit, 90 ... Discharge Paper

Claims (6)

The recording medium is continuously transported at a constant speed, and after applying a treatment liquid that agglomerates the ink coloring material over the entire coating area set in advance on the recording medium, the recording medium is intermittently transported on the recording medium. In an ink jet recording method for recording an image by ejecting ink droplets with a serial type recording head,
Determine the amount of penetration of the treatment liquid to the recording medium at the time of ink ejection, the so ink droplets droplet ejection by the recording head reaches a predetermined fixing dot diameter, droplet ejection of ink in accordance with the amount of penetration was determined An ink jet recording method, wherein an ink droplet is ejected by correcting an amount.   2. The penetration amount is obtained for each width region subjected to main scanning from the obtained time after obtaining a time from when the treatment liquid is applied to when main scanning by the recording head is started. Inkjet recording method. Based on the relationship between the previously determined amount of penetration and the fixing dot diameter of the treatment liquid to the recording medium such that said ink droplets droplet ejection by the recording head reaches a predetermined fixing dot diameter, correcting the ink volume The ink jet recording method according to claim 1, wherein the ink jet recording method is performed. Continuous conveying means for continuously conveying the recording medium at a constant speed;
Treatment liquid application means for applying a treatment liquid for aggregating the colorant of the ink onto the recording medium continuously conveyed by the continuous conveyance means;
Intermittent transport means for intermittently transporting the recording medium to which the treatment liquid has been applied to the entire coating region set in advance ;
Ink droplet ejection means for ejecting ink droplets with a serial type recording head onto a recording medium intermittently conveyed by the intermittent conveyance means;
Determine the amount of penetration of the treatment liquid to the recording medium at the time of ink ejection, the so ink droplets droplet ejection by the recording head reaches a predetermined fixing dot diameter, droplet ejection of ink in accordance with the amount of penetration was determined Droplet ejection amount correcting means for correcting the amount;
An ink jet recording apparatus comprising:   The droplet ejection amount correcting means obtains the time from the application of the treatment liquid to the start of main scanning by the recording head, and obtains the permeation amount for each width region to be main scanned from the obtained time. The inkjet recording apparatus according to claim 4. The droplet ejection amount correcting means is configured so that the ink droplets ejected by the recording head have a predetermined fixing dot diameter based on the relationship between the penetration amount of the processing liquid into the recording medium and the fixing dot diameter obtained in advance. The ink jet recording apparatus according to claim 4, wherein the ink droplet ejection amount is corrected.

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