JP2007030201A - Liquid drop ejector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration in image quality and frequency of occurrence of poor conveyance resulting from deformation of a sheet with print on the surface, in an ink jet recorder making printing on the front and rear surfaces of the sheet. <P>SOLUTION: When image information of printing on the front and rear surfaces is received, printing rate of the image information on the front surface is compared with printing rate of the image information on the rear surface. If the printing rate of image information on the front surface is higher than that on the rear surface, print processing is performed by replacing the image information on the front surface with the rear surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a droplet discharge device capable of printing on both front and back sides of a sheet by a droplet discharge head.

  Inkjet recording devices that can print on both front and back sides of paper have a problem of so-called “image back-through”, in which an image printed on one side can be seen through from the other side. Various countermeasures have been devised (see, for example, Patent Documents 1 and 2). Further, as another problem, there is a paper conveyance failure that occurs when the paper printed on the front surface is conveyed along a conveyance path for reversing the front and back.

  This paper conveyance failure occurs because the paper that has been wet and deformed by the ink is conveyed by a reversing conveyance path that is refracted long, and the paper printed on the surface of the paper is reversed so that the image is not disturbed. The frequency of occurrence increases because the contact pressure of the transport rollers on the transport path for the paper is set low. In particular, in a full-line head type inkjet recording device that prints over the entire width of the paper when the length of the recording head is equal to or greater than the width of the paper, the printing speed is fast and the drying time of the ink on the surface of the paper is secured. Since this is not possible, a paper conveyance failure is likely to occur. In addition, when printing is performed on the surface of the paper with a large amount of image or the like, the amount of ink on the surface of the paper is increased, and the amount of deformation of the paper is increased. .

  In addition, in the case of using an electrostatic adsorption conveyance method in which printing is performed while electrostatically adsorbing a sheet to a conveyance belt, even if the deformed sheet printed on the surface is electrostatically adsorbed to the conveyance belt, Since the gap between the recording head and the paper cannot be ensured accurately, image quality degradation on the back side of the paper, paper jam due to contact between the recording head and the paper, and the like occur.

Note that, as described above, a countermeasure method for preventing the back-through of the image at the time of double-sided printing in the inkjet recording apparatus has been devised, but the paper generated due to the deformation of the paper at the time of double-sided printing in the inkjet recording apparatus No measures have been devised to prevent poor transport and image quality degradation on the back of the paper.
Japanese Patent Laid-Open No. 2003-341033 JP 2001-310506 A

  The present invention has been made in consideration of the above facts, and in an inkjet recording apparatus capable of printing on both the front and back sides of a sheet, the occurrence frequency and image quality of sheet conveyance failure caused by deformation of the sheet printed on the surface Suppresses the decline.

  The droplet discharge device according to claim 1, a transfer unit that transfers a sheet, a droplet discharge head that discharges and prints droplets on a sheet that is transferred by the transfer unit, and a surface by the droplet discharge head A liquid ejection unit comprising: a reversing unit configured to reverse the front and back of the sheet printed on the sheet and to convey the sheet to the upstream side in the conveyance direction of the conveying unit; and a head control unit configured to control driving of the liquid droplet ejection head according to image information. 1st image information correction means for reducing the surface printing amount to a predetermined value or less and transmitting it to the head control means when the printing amount on the surface of the received image information for front and back duplex printing is higher than a predetermined value. It is characterized by having.

  In the liquid droplet ejection apparatus according to claim 1, the drive of the liquid droplet ejection head is controlled according to the image information by the head control unit, and the liquid droplet is ejected from the liquid droplet ejection head onto the surface of the sheet conveyed by the conveyance unit. And printed. Then, the sheet printed on the front surface is turned upside down by the reversing unit and conveyed to the upstream side in the conveying direction of the conveying unit, and the driving of the droplet discharge head is controlled again by the head control unit according to the image information. Then, droplets are ejected from the droplet ejection head and printed on the back surface of the sheet conveyed by the conveying means.

  Here, the image information of the front and back double-sided printing is first received by the first image information correcting unit, and when the surface printing amount is higher than a predetermined value, the first image information correcting unit sets the surface printing amount to a predetermined value. After being lowered to the following, it is transmitted to the head control means.

  That is, by reducing the amount of printing on the surface of the sheet to a predetermined value or less and reducing the amount of liquid on the surface of the sheet to a predetermined amount or less, deformation of the sheet after printing on the surface is suppressed to a predetermined level or less. Yes.

  Thereby, the occurrence frequency of the conveyance failure of the sheet conveyed by the reversing unit after printing on the surface is suppressed. Also, since the posture of the sheet conveyed by the conveying means after printing on the surface is stabilized, the occurrence frequency of sheet conveyance failure due to the contact between the sheet and the droplet discharge head is suppressed, and the sheet and liquid An error in the gap with the droplet discharge head is suppressed, and deterioration in image quality on the back surface of the sheet is suppressed.

  The liquid droplet ejection apparatus according to claim 2 is the liquid droplet ejection apparatus according to claim 1, further comprising sheet determination means for determining a sheet type, wherein the first image information correction means is the sheet determination apparatus. When the sheet type determined by the means is a predetermined type, the image information is transmitted to the head control means without being corrected.

  In the liquid droplet ejection apparatus according to claim 2, when the sheet type is determined by the sheet determining unit, and the sheet type determined by the sheet determining unit is a predetermined type such as double-sided printing paper, The image information is transmitted from the first image information correction unit to the head control unit without being corrected.

  In other words, in the case of a sheet that is easily deformed by droplets that land on the surface, such as weak paper, the sheet that is conveyed by the reversing means or the conveying means by reducing the printing amount on the surface to a predetermined value or less. The occurrence frequency of the conveyance failure is suppressed, and the deterioration of the image quality on the back side of the sheet is suppressed. On the other hand, in the case of a sheet that is difficult to be deformed by droplets that have landed on its surface, such as strong paper, it is difficult for sheet conveyance failure and image quality on the back side of the sheet to occur. The density and resolution of the sheet surface are maintained while keeping it higher, and deterioration of image quality on the sheet surface is suppressed.

  The droplet discharge device according to claim 3, a transfer unit that transfers a sheet, a droplet discharge head that discharges and prints droplets on a sheet that is transferred by the transfer unit, and a surface by the droplet discharge head. A liquid ejection unit comprising: a reversing unit configured to reverse the front and back of the sheet printed on the sheet and to convey the sheet to the upstream side in the conveyance direction of the conveying unit; and a head control unit configured to control driving of the liquid droplet ejection head according to image information. 2nd image information correction which is apparatus, and replaces the image information of front side and back side, and transmits to the said head control means, when the amount of printing is higher in the front side and the back side of the image information of the received front and back double-sided printing It has the means.

  In the droplet discharge device according to claim 3, the drive of the droplet discharge head is controlled in accordance with the image information by the head control unit, and the droplet is discharged from the droplet discharge head onto the surface of the sheet conveyed by the conveyance unit. And printed. Then, the sheet printed on the front surface is turned upside down by the reversing unit and conveyed to the upstream side in the conveying direction of the conveying unit, and the driving of the droplet discharge head is controlled again by the head control unit according to the image information. Then, droplets are ejected from the droplet ejection head and printed on the back surface of the sheet conveyed by the conveying means.

  Here, the image information of the front and back double-sided printing is first received by the second image information correcting unit, and when the front side and the back side have a higher printing amount on the front side, the second image information correcting unit causes the front and back side image to be printed. After the information is replaced, it is transmitted to the head control means.

  That is, the image after printing on the front surface is reduced by turning the image with a high printing amount such as an image on the back surface and turning the image with a low printing amount such as text on the surface to reduce the amount of liquid on the surface of the sheet. The deformation is suppressed.

  Thereby, the occurrence frequency of the conveyance failure of the sheet conveyed by the reversing unit after printing on the surface is suppressed. Also, since the posture of the sheet conveyed by the conveying means after printing on the surface is stabilized, the occurrence frequency of sheet conveyance failure due to the contact between the sheet and the droplet discharge head is suppressed, and the sheet and liquid An error in the gap with the droplet discharge head is suppressed, and deterioration in image quality on the back surface of the sheet is suppressed. Furthermore, since the printing amount on both the front and back sides of the sheet is maintained, the density and resolution on both the front and back sides of the sheet are maintained, and deterioration in image quality on both the front and back sides of the sheet is suppressed.

  A droplet discharge device according to a fourth aspect of the present invention is the droplet discharge device according to the third aspect, further comprising a discharge control unit that controls driving of the reversing unit, and the discharge control unit includes the first discharge control unit. The driving of the reversing unit is controlled such that when printing is performed on the sheet according to the image information corrected by the two-image information correcting unit, the sheet is reversed and discharged.

  In the droplet discharge device according to the fourth aspect, the driving of the reversing means is controlled by the paper discharge control means. The sheet discharge control unit prints on the sheet according to the image information corrected by the second image information correction unit, and the front and back of the sheet conveyed to the downstream side in the conveyance direction of the droplet discharge head are reversed. Then, the driving of the reversing means is controlled, and the sheet is reversed and discharged. As a result, the front and back directions of the discharged sheet are correct.

  The droplet discharge device according to claim 5 is the droplet discharge device according to claim 3 or 4, further comprising sheet determination means for determining a sheet type, wherein the second image information correction means is When the sheet type determined by the sheet determination unit is a predetermined type, the image information is transmitted to the head control unit without correction.

  In the droplet discharge device according to claim 5, when the sheet type is determined by the sheet determination unit, and the sheet type determined by the sheet determination unit is a predetermined type such as paper dedicated for double-sided printing. The image information is transmitted from the second image information correction unit to the head control unit without being corrected.

  In other words, in the case of a sheet that is easily deformed by droplets that have landed on the surface, such as weak paper, the printing order on the front surface and the back surface is changed to reduce the printing amount on the front surface. The frequency of occurrence of poor conveyance of the conveyed sheet is suppressed, and deterioration in image quality on the back side of the sheet is suppressed. On the other hand, in the case of a type of sheet that is difficult to be deformed by droplets that land on the front surface, such as strong paper, it is difficult for sheet conveyance failure and image quality deterioration on the back side of the sheet to occur. maintain.

  The droplet discharge device according to claim 6, a transfer unit that transfers a sheet, a droplet discharge head that discharges and prints droplets on a sheet that is transferred by the transfer unit, and a surface by the droplet discharge head. A liquid ejection unit comprising: a reversing unit configured to reverse the front and back of the sheet printed on the sheet and to convey the sheet to the upstream side in the conveyance direction of the conveying unit; and a head control unit configured to control driving of the liquid droplet ejection head according to image information. And a third image information correction unit that rotates the image information by 180 degrees and transmits the image information to the head control unit when the first half and the second half of the received image information have a higher printing amount. Features.

  In the droplet discharge device according to claim 6, the drive of the droplet discharge head is controlled according to the image information by the head control unit, and the droplet is discharged from the droplet discharge head onto the surface of the sheet conveyed by the conveyance unit. And printed. Then, the sheet printed on the front surface is turned upside down by the reversing unit and conveyed to the upstream side in the conveying direction of the conveying unit, and the driving of the droplet discharge head is controlled again by the head control unit according to the image information. Then, droplets are ejected from the droplet ejection head and printed on the back surface of the sheet conveyed by the conveying means.

  Here, the image information is first received by the third image information correcting unit, and when the first half and the latter half have a higher printing amount, the third image information correcting unit rotates the image information by 180 degrees. That is, the first half and the second half are switched, and then transmitted to the head control means.

  That is, by turning an image with a high printing amount such as an image in the second half and an image with a low printing amount such as a text in the first half, the amount of liquid at the leading end of the sheet (upstream end in the conveying direction) is reduced, and the surface The deformation of the leading end of the sheet after the image is recorded is suppressed.

  Thereby, the occurrence frequency of the conveyance failure of the sheet conveyed by the reversing unit after the image is recorded on the surface is suppressed. Further, since the printing amount on both the front and back sides of the sheet is maintained, the density and resolution on both the front and back sides of the sheet are maintained, and deterioration in image quality on both the front and back sides of the sheet is suppressed.

  The droplet discharge device according to claim 7 is the droplet discharge device according to claim 6, further comprising sheet determination means for determining a sheet type, wherein the third image information correction means is the sheet determination device. When the sheet type determined by the means is a predetermined type, the image information is transmitted to the head control means without being corrected.

  In the droplet discharge device according to claim 7, when the sheet type is determined by the sheet determining unit, and the sheet type determined by the sheet determining unit is a predetermined type such as paper dedicated for double-sided printing. The image information is transmitted from the third image information correction unit to the head control unit without being corrected.

  That is, in the case of a kind of sheet that is easily deformed by droplets that have landed on its surface, such as weak paper, it is conveyed by the reversing means by changing the printing direction before and after and reducing the printing amount in the first half. Reduces the frequency of sheet conveyance failures. On the other hand, in the case of a type of sheet that is difficult to be deformed by droplets that have landed on the front surface, such as strong paper, it is difficult to cause poor conveyance and lower image quality on the back surface, so the printing orientation is maintained.

  The droplet discharge device according to claim 8 is the droplet discharge device according to any one of claims 1 to 7, wherein the user is notified that the printing process is executed with the image information corrected. It has the correction notification means to do.

  In the droplet discharge device according to the eighth aspect, the user is notified by the notification means such as a display panel that the printing process is executed with the image information corrected. As a result, the user can see that the printing amount on the front side of the sheet has decreased, the printing order of the front and back sides of the sheet has been switched, or the printing direction has changed between before and after the sheet. You can know that you are.

  The droplet discharge device according to claim 9 is the droplet discharge device according to any one of claims 1 to 8, wherein the permission or non-permission of the printing process executed by correcting the image information is selected. A selection notifying means for notifying the user of the image processing, a selection means for allowing the user to select permission / non-permission of the printing process performed by correcting the image information, and a result selected by the selection means. Drive permission control means for controlling permission / non-permission of driving of the droplet discharge head.

  In the droplet discharge device according to the ninth aspect, the selection notifying means such as a display panel is notified to the user that the printing process to be executed by correcting the image information is selected. Then, when permission / non-permission is selected by the selection unit provided to allow the user to select permission / non-permission of the printing process executed by correcting the image information, the drive permission control unit selects the selection unit. According to the result selected by (1), permission / non-permission of driving of the droplet discharge head is controlled.

  As a result, the user can select whether to perform double-sided printing by reducing the amount of printing on the front surface or to switch to single-sided printing.

  Since the present invention is configured as described above, in an ink jet recording apparatus capable of printing on both the front and back surfaces of a sheet, it is possible to suppress the occurrence frequency of sheet conveyance failure and image quality degradation caused by deformation of the sheet printed on the surface.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an ink jet recording apparatus 12 of the present embodiment. A paper feed tray 16 is provided in the lower part of the casing 14 of the ink jet recording apparatus 12, and the sheets P stacked in the paper feed tray 16 can be taken out one by one by a pickup roll 18. The taken paper P is transported by a plurality of transport roller pairs 20 constituting a predetermined transport path 22.

  Above the paper feed tray 16, an endless transport belt 28 is stretched around a drive roll 24 and driven rolls 26 and 27. A recording head array 30 is disposed above the conveyor belt 28 and faces the flat portion 28F of the conveyor belt 28. This opposed area is an ejection area SE where ink droplets are ejected from the recording head array 30. The sheet P transported along the transport path 22 is held by the transport belt 28 and reaches the discharge area SE, and ink droplets corresponding to image information are attached from the recording head array 30 in a state of facing the recording head array 30. The

  In this embodiment, the recording head array 30 has a long shape in which the effective recording area is equal to or larger than the width of the paper P (the length in the direction orthogonal to the transport direction), and is yellow (Y) and magenta (M). , Cyan (S), and four inkjet recording heads (hereinafter referred to as recording heads) 32 corresponding to the four colors of black (K) are arranged along the transport direction, so that a full-color image can be recorded. ing.

  Each recording head 32 is controlled by the head driving unit 100. The head drive unit 100 is configured to, for example, determine the ink droplet ejection timing and the ink ejection port (nozzle) to be used according to the image information and send a drive signal to the recording head 32.

  The recording head array 30 may be stationary in a direction orthogonal to the transport direction. However, if the recording head array 30 is configured to move as necessary, an image with higher resolution can be obtained by multi-pass image recording. Or the failure of the recording head 32 is not reflected in the recording result.

  Four maintenance units 34 corresponding to the respective recording heads 32 are arranged on both sides of the recording head array 30. As shown in FIG. 2, when maintenance is performed on the recording head 32, the recording head array 30 moves upward, and the maintenance unit 34 moves into the gap formed between the conveyance belt 28 and enters. Then, a predetermined maintenance operation (suction, wiping, capping, etc.) is performed while facing the nozzle surface.

  As shown in FIG. 3, a charging roll 36 to which a power source 38 is connected is disposed on the upstream side of the recording head array 30. The charging roll 36 is driven while sandwiching the conveyance belt 28 and the paper P with the driven roll 26, and moves between a pressing position for pressing the paper P against the conveyance belt 28 and a separation position separated from the conveyance belt 28. It is possible. At the pressing position, a predetermined potential difference is generated between the grounded driven roll 26 and the sheet P can be charged and electrostatically attracted to the transport belt 28.

  A separation plate 40 is disposed on the downstream side of the recording head array 30 and separates the paper P from the conveyance belt 28. The peeled paper P is conveyed by a discharge roller pair 42 that forms a discharge path 44 on the downstream side of the peeling plate 40 and is discharged to a paper discharge tray 46 provided on the side of the housing 14, or The paper is transported by a plurality of transport roller pairs 50 constituting a reversal transport path 48 that branches from the paper discharge path 44, is turned upside down, and is transported to the upstream end of the transport belt 28 in the transport direction.

  As shown in FIG. 4, the inkjet recording apparatus 12 is built in a scanner 120 (see FIG. 5A) or an external device 122 (see FIG. 5B) such as a personal computer installed in the apparatus. A receiving unit 104 that receives image information, paper information, and the like transmitted from the transmitting unit 102, an image information correcting unit 106 that corrects the image information received by the receiving unit 104 and transmits the image information to the head driving unit 100, and a touch panel (FIG. 5). (Refer to FIG. 10), a touch panel control unit 110 that controls 108, a drive permission control unit 112 that controls permission / non-permission of driving of the recording head 32, and a sheet determination unit 114 that determines the type of the sheet.

  The image information includes printing rate information, and the image density is transmitted as the printing rate from the transmitting unit 102 to the receiving unit 104. The head driving unit 100 determines a printing amount according to the printing rate, The printing process is being executed. Therefore, the printing rate may be controlled to control the printing amount.

  Here, a first embodiment of the double-sided printing control method will be described with reference to the flowchart of FIG.

  First, when the reception unit 104 receives image information from the transmission unit 102, a processing routine is started, and the process proceeds to step 1. In step 1, the image information correction unit 106 determines whether the image information is for front and back double-sided printing. If the determination is affirmative, the process proceeds to step 2. If the determination is negative, the process proceeds to step 12. In step 12, the image information is transmitted from the image information correction unit 106 to the head driving unit 100 without being corrected. Then, the head driving unit 100 drives the recording head 32 according to the image information. As a result, an image is printed on the surface of the paper P with the printing rate of the image information transmitted from the transmission unit 102 and the front and rear printing directions. Then, the processing routine ends.

  On the other hand, in step 2, the paper determination unit 114 determines whether the type of the paper P set on the touch panel 108 or the external device 122 is a paper dedicated for double-sided printing. Then, the process proceeds to step 13. In step 13, the image information is transmitted from the image information correction unit 106 to the head driving unit 100 without being corrected. Then, the head driving unit 100 drives the recording head 32 according to the image information. As a result, images are printed on both the front and back sides of the paper P with the printing rate of the image information transmitted from the transmitting unit 102, the front and back printing order, and the front and back orientation. Then, the processing routine ends.

  On the other hand, in step 3, the image information correction unit 106 calculates the front side print rate and the back side print rate. Next, in step 4, it is determined whether or not the surface printing rate calculated in step 3 is larger than the threshold shown in the table of FIG. 7. If affirmative, the process proceeds to step 5, and if negative, the process proceeds to step 13. . In step 13, the image information is transmitted from the image information correction unit 106 to the head driving unit 100 without being corrected. Then, the head driving unit 100 drives the recording head 32 according to the image information. As a result, images are printed on both the front and back sides of the paper P with the printing rate of the image information transmitted from the transmitting unit 102, the front and back printing order, and the front and back orientation. On the other hand, in step 5, it is determined whether or not the printing rate of the back side image information is larger than the threshold shown in the table of FIG. 7. If the result is negative, the process proceeds to step 6;

  In step 6, the touch panel 108 is controlled by the touch panel control unit 110, and as shown in FIG. 8A, “This is not a double-sided paper. If double-sided printing is performed with this print, the back side will be up and discharged. Is displayed on the touch panel 108. The warning display “??” and the selection keys “Yes”, “No”, and “Cancel” are displayed. Alternatively, the warning display and the selection key are displayed on the monitor of the external device 122.

  Next, in Step 7, it is determined which selection key “Yes”, “No”, or “Cancel” is selected by the touch panel 108 or the external device 122. If “Yes”, the process proceeds to Step 8, “No”, If it is “Cancel”, the process proceeds to Step 9.

  In step 8, the image information correction unit 106 replaces the image information on the back side of the front side, and the process proceeds to step 13. In step 13, image information of front and back double-sided printing in which the front and back surfaces are reversed is transmitted from the image information correction unit 106 to the head driving unit 100. Then, the head driving unit 100 drives the recording head 32 according to the corrected image information. As a result, as shown in FIG. 9, images are printed on both the front and back sides of the paper P in a state where the print order of the image information transmitted from the transmission unit 102 is reversed. Then, the processing routine ends.

  On the other hand, in Step 9, the touch panel 108 is controlled by the touch panel control unit 110, and as shown in FIG. 8, “It is not a double-sided exclusive paper. If double-sided printing is performed with this print, the surface density will decrease slightly. And a selection key such as “Yes”, “No”, and “Cancel” are displayed. Alternatively, the warning display and the selection key are displayed on the monitor of the external device 122. Next, in step 10, it is determined which selection key “Yes”, “No”, or “Cancel” is selected by the touch panel 108 or the external device 122. If “Yes”, the process proceeds to Step 11. If it is “Cancel”, the process proceeds to Step 14. In step 11, the image information correction unit 106 reduces the printing rate of the surface image information to the threshold value in step 4, and the process proceeds to step 13. In step 13, image information whose surface printing rate has been reduced is transmitted from the image information correction unit 106 to the head driving unit 100, and the drive of the recording head 32 is permitted from the drive permission control unit 112 to the head driving unit 100. Signal is transmitted. Then, the head driving unit 100 drives the recording head 32 according to the corrected image information. As a result, images are printed on both the front and back sides of the paper P in a state where the printing rate of the front surface of the image information transmitted from the transmission unit 102 is reduced.

  On the other hand, in step 14, a signal for disabling the drive of the recording head 32 is transmitted from the drive permission control unit 112 to the head drive unit 100, and the processing routine ends without executing printing.

  Here, as shown in the table of FIG. 7, in this embodiment, the threshold of the printing rate for thin paper and recycled paper is 50%, and the threshold of the printing rate for plain paper is 100%. The area ratio of dots included in the unit area of P is 100% for a single-color full-color image and 400% for a four-color full-color full-color image.

  Note that the amount of ink (moisture amount) contained in the unit area of the paper P affects the deformation amount of the paper P. If the resolution and the ink amount per dot are constant, the amount of ink is shown in the graph of FIG. Thus, there is a correlation between the printing rate (printing amount) and the deformation amount of the paper P. In the present embodiment, the resolution is 600 × 1200 dpi, the ink amount per dot is 6 pl (picoliter), and printing is performed on the entire A4 paper P at a printing rate of 50%, the ink in the paper P The amount is 0.21 ml (= 6 pl × 600 dpi × 1200 dpi × 210 mm / 25.4 inch × 297 mm / 25.4 inch × 50%).

  That is, the printing rate threshold value may be set so that the ink amount contained in the paper P is 0.21 ml or less. For example, when the resolution is 600 × 1200 dpi and the ink amount per dot is 4 pl. The threshold of the printing rate is 75%.

  As described above, in the ink jet recording apparatus 12 of the present embodiment, in the case of the type of paper P that is easily deformed by containing moisture, such as thin paper or recycled paper, an image having a high printing rate such as an image is turned to the back side and text By rotating an image with a low printing rate such as a surface to the surface, the amount of ink adhering to the surface of the paper P is reduced, and the deformation amount of the paper P after the image is printed on the surface is suppressed. Thereby, the occurrence frequency of the conveyance failure of the paper P conveyed on the reverse conveyance path 48 after the image is printed on the surface is suppressed. Further, since the posture of the sheet P conveyed by the conveying belt 28 after the image is printed on the surface is stabilized, the occurrence frequency of the conveyance failure of the sheet P due to the contact between the sheet P and the recording head 32 is suppressed. In addition, an error in the gap between the paper P and the recording head 32 is suppressed, and deterioration of the image quality on the back surface of the paper P is suppressed. Furthermore, since the printing rate on both the front and back sides of the paper P can be maintained, the density and resolution on both the front and back sides can be maintained.

  If the printing rate of the front and back sides of the image information is higher than the threshold value and there is no effect even if the printing order is switched between the front side and the back side, only the front side printing rate is lowered to the threshold value or less, thereby The amount of ink adhering to the ink is reduced, and the deformation amount of the paper P after the image is recorded on the surface is suppressed.

  In addition, when the image information is corrected by the image information correction unit 106, the user is notified, and whether the printing process according to the corrected image information is permitted or not is prohibited. The user is supposed to choose. For this reason, if the printing process is permitted, the user can grasp that the direction of the discharged paper P is reversed between the front and back sides, or the density and resolution are reduced. Immediately, the front and back directions of the paper P can be switched, and the density and resolution can be confirmed. When the printing process is not permitted, the type of the paper P can be changed or switched to single-sided printing.

  Further, when the type of the paper P is a double-sided exclusive paper, it is difficult to cause a conveyance failure of the paper P and a deterioration in image quality on the back side of the paper. Therefore, the front and back images are not interchanged, and the printing rate on the front side is not reduced. By doing so, the printing order of the front and back surfaces is maintained, and the density and resolution of both the front and back surfaces are maintained.

  Next, a method for discharging the paper P printed on both sides will be described.

  As shown in FIG. 1, a conveyance path switching guide 52 is disposed at a branch point between the discharge path 44 and the reverse conveyance path 48. The transport path switching guide 52 is driven by a drive mechanism 54 such as a motor or a solenoid, and closes the discharge path 44 and opens the reverse transport path 48 or closes the reverse transport path 48 and opens the discharge path 44. To do.

  The reverse conveyance path 48 includes a first reverse conveyance path 48A that extends downward from the discharge path 44 and a second reverse conveyance path 48B that branches at the center of the first reverse conveyance path 48A and joins the conveyance path 22. The conveyance path switching guide 56 is disposed at a branch point between the first reverse conveyance path 48A and the second reverse conveyance path 48B. The transport path switching guide 56 is driven by a drive mechanism 58 such as a motor or a solenoid, and closes the first reverse transport path 48A and opens the second reverse transport path 48B, or closes the second reverse transport path 48B. Then, the first reverse conveyance path 48A is opened. The plurality of transport roller pairs 50 constituting the reverse transport path 48 are driven by a motor 60 that can rotate forward and backward.

  Here, the drive mechanisms 54 and 58 and the motor 60 are controlled by the paper discharge control unit 62. Hereinafter, a discharge control method by the discharge control unit 62 will be described with reference to a flowchart of FIG.

  When the double-sided printing process is executed, the processing routine is started and the process proceeds to step 100. In step 100, it is determined whether the printing order of the front side and the back side has been switched. If the determination is affirmative, the process proceeds to step 101. If the determination is negative, the process proceeds to step 102. In step 101, the drive mechanism 54 is driven, and the discharge path 44 is closed and the reverse transfer path 44 is opened by the transfer path switching guide 52. Further, the drive mechanism 58 is driven, and the second reverse transport path 48B is closed and the first reverse transport path 48A is opened by the transport path switching guide 56. Further, the motor 60 is rotated forward to transport the paper P to the downstream end portion in the transport direction of the first reverse transport path 48A. Thereafter, the motor 60 is rotated in the reverse direction, and the paper P is transported upstream in the transport direction of the first reverse transport path 48A. Next, in step 102, the paper P is conveyed by the discharge roller pair 42 through the discharge path 44 and discharged to the discharge tray 46. Then, the processing routine ends.

  As described above, when the printing order of the front surface and the back surface is changed, the front and back sides of the paper P to be discharged are made to be correct by discharging the paper after turning it upside down. be able to.

  If printing is performed on the back side of the paper P that has been printed and deformed on the front surface, deformation in the reverse direction occurs and the amount of deformation is reduced as a whole. Even if it passes through 48, it is unlikely that a conveyance failure will occur.

  Next, a second embodiment of the double-sided printing control method will be described with reference to the flowchart of FIG.

  First, when the reception unit 104 receives image information from the transmission unit 102, a processing routine is started and the process proceeds to step 200. In step 200, it is determined by the paper determination unit 114 whether or not the type of the paper P set on the touch panel 108 or the external device 122 is the paper P dedicated to double-sided printing. Then, the process proceeds to step 210. In step 210, the image information is transmitted from the image information correction unit 106 to the head driving unit 100 without being corrected. Then, the head driving unit 100 drives the recording head 32 according to the image information. As a result, an image is printed on the paper P with the printing rate of the image information transmitted from the transmission unit 102, the front and back printing order, and the front and back orientation. Then, the processing routine is ended.

  On the other hand, in step 201, the image information correction unit 106 calculates the printing rate of the first half of the image information and the printing rate of the second half of the surface. Next, in step 202, it is determined whether or not the printing ratio in the first half of the front surface calculated in step 201 is larger than the threshold shown in the table of FIG. move on. In step 210, the image information is transmitted from the image information correction unit 106 to the head driving unit 100 without being corrected. Then, the head driving unit 100 drives the recording head 32 according to the image information. As a result, an image is printed on the paper P with the printing rate of the image information transmitted from the transmission unit 102, the front and back printing order, and the front and back orientation. On the other hand, in step 203, it is determined whether or not the printing rate of the second half of the front surface of the image information is larger than the threshold shown in the table of FIG.

  In step 204, the touch panel control unit 110 controls the touch panel 108, and as shown in FIG. 13A, “It is not a double-sided exclusive paper. A warning display “Are you sure?” And selection keys “Yes”, “No”, and “Cancel” are displayed on the touch panel 108. Alternatively, the warning display and the selection key are displayed on the monitor of the external device 122.

  Next, in Step 205, it is determined which selection key “Yes”, “No”, or “Cancel” has been selected by the touch panel 108 or the external device 122. If “Yes”, the process proceeds to Step 206, “No”, If it is “cancel”, the process proceeds to step 207.

  In step 206, the image information correction unit 106 rotates the image information by 180 degrees, and the process proceeds to step 210. In step 210, image information in which the printing direction is switched between the first half and the second half is transmitted from the image information correction unit 106 to the head driving unit 100. Then, the head driving unit 100 drives the recording head 32 according to the corrected image information. As a result, as shown in FIG. 14, an image is printed on the paper P in a state where the print direction of the image information transmitted from the transmission unit 102 is reversed in the front and rear directions. Then, the processing routine ends.

  On the other hand, in step 207, the touch panel 108 is controlled by the touch panel control unit 110, and as shown in FIG. 13B, “This is not a double-sided paper. If double-sided printing is performed with this print, the surface density will be slightly reduced. Is displayed, and a selection key of “Yes”, “No”, and “Cancel” is displayed. Alternatively, the warning display and the selection key are displayed on the monitor of the external device 122. Next, in Step 208, it is determined which selection key “Yes”, “No”, or “Cancel” has been selected by the touch panel 108 or the external device 122. If “Yes”, Step 209 is followed by “No”, “ If it is “cancel”, the process proceeds to step 211. In step 209, the image information correction unit 106 reduces the printing rate of the surface image information to the threshold value in step 202, and the process proceeds to step 210. In step 210, image information with a reduced surface printing rate is transmitted from the image information correction unit 106 to the head driving unit 100, and driving of the recording head 32 is permitted from the driving permission control unit 112 to the head driving unit 100. Signal is transmitted. Then, the head driving unit 100 drives the recording head 32 according to the corrected image information. As a result, the image is printed on the paper P in a state where the printing rate of the surface of the image information transmitted from the transmission unit 102 is reduced.

  On the other hand, in step 211, a signal for disabling the drive of the recording head 32 is transmitted from the drive permission control unit 112 to the head driving unit 100, and the processing routine ends without executing printing.

In the present embodiment, the printing rates of the first half and the second half of the paper P are compared. However, the deformation amount of the paper P is large at the leading edge and the trailing edge of the paper P, and the paper P is particularly large. For example, the leading edge and the trailing edge of the paper P are compared with each other 5 to 50 mm, or the leading and trailing corners of the paper P are compared with each of 25 to 2500 mm ^2. Is effective.

  As described above, in the inkjet recording apparatus 12 of the present embodiment, an image having a high printing rate such as an image is rotated in the second half, and an image having a low printing rate such as a text is rotated in the first half. Part) is reduced, and the amount of deformation at the front end of the paper P after the image is recorded on the surface is suppressed. Thereby, the occurrence frequency of the conveyance failure of the paper P conveyed on the reverse conveyance path 48 after the image is recorded on the surface is suppressed.

  In addition, since the posture of the paper P being transported by the transport belt 28 after the image is recorded on the surface is stabilized, the frequency of occurrence of poor transport of the paper P due to the contact between the paper P and the recording head 32 is suppressed. In addition, an error in the gap between the paper P and the recording head 32 is suppressed, and deterioration of the image quality on the back surface of the paper P is suppressed. Furthermore, since the printing rate on both the front and back sides of the paper P can be maintained, the density and resolution on both the front and back sides can be maintained.

  If the printing rate of the front half of the image information is higher than the threshold value and there is no effect even if the printing direction is switched between the first half and the second half, only the printing rate of the front side of the image information is reduced below the threshold value. The amount of moisture in the first half of the surface of the paper P is reduced, and the amount of deformation of the paper P after the image is recorded on the surface is suppressed.

  In addition, when the image information is corrected by the image information correction unit 106, the user is notified, and whether the printing process according to the corrected image information is permitted or not is prohibited. The user is supposed to choose. For this reason, when the printing process is permitted, the user can grasp that the direction of the discharged paper P is reversed in the front and back, and the density and resolution are reduced. It is possible to change the front and rear direction of the paper P, and to check the density and resolution. When the printing process is not permitted, the type of the paper P can be changed or switched to single-sided printing.

  In addition, when the type of paper P is a double-sided special paper, it is difficult to cause poor conveyance and lower image quality on the back side. Therefore, the direction of printing is not changed between front and back, and the front side printing rate is not reduced. Thus, the orientation of the front and rear printing is maintained, and the density and resolution on both the front and back sides are maintained.

  In the present embodiment, the present invention has been described by taking an example of a method of controlling the printing amount by changing the printing rate, but a method of changing the printing amount by changing the droplet volume is also applicable. .

  Further, in the present embodiment, the ink jet recording apparatus has been described as an example of the ink jet recording apparatus. However, the liquid droplet ejecting apparatus of the present invention is not limited to the ink jet recording apparatus, and a colored ink is formed on a polymer film. Applicable to general droplet ejection devices for various industrial applications, such as the production of color filters for displays performed by discharging liquid and the formation of EL display panels performed by discharging organic EL solutions onto a film It is.

  In addition, the “recording medium” that is a target of image recording in the droplet discharge device of the present invention includes a wide range of objects as long as the droplet discharge head discharges droplets. Accordingly, the recording medium includes recording paper, an OHP sheet, and the like, but also includes, for example, a film serving as a base material for a display panel.

  Further, “printing” performed in the droplet discharge device of the present invention is not limited to the formation of characters and symbols, and “printing” includes the formation of patterns such as images.

  The “printing amount” used in the present invention means “amount of liquid applied to a certain area”. In addition, the “printing ratio” used in the embodiment of the present invention is “(a) when the droplet diameter is constant: a ratio in which an image included in a certain region is ON (liquid application), (b) a droplet. In the case of a plurality of diameters: a weight corresponding to the droplet diameter (or appropriate amount) is given, and for a certain region, for each pixel of the pixels included in the region (in accordance with image information), the droplet diameter of the droplet applied to the pixel The value obtained by dividing the first value obtained by adding the weight corresponding to the value by the second value obtained by adding the weight corresponding to the maximum droplet diameter to all pixels included in the region " It is.

  Furthermore, in the present embodiment, the present invention has been described by taking an example of a configuration including an inkjet recording head that is longer than the width of the paper P. However, the present invention is not limited thereto, and for example, an inkjet that is shorter than the width of the paper P. The present invention can also be applied to a configuration in which the recording head is moved in the width direction of the paper P.

1 is a diagram showing an outline of an ink jet recording apparatus according to an embodiment of the present invention. 1 is a diagram showing an outline of an ink jet recording apparatus according to an embodiment of the present invention. It is a figure which shows the outline of the printing part of the inkjet recording device of embodiment of this invention. 1 is a block diagram illustrating a schematic configuration of an electric system of an ink jet recording apparatus according to an embodiment of the present invention. 1 is a perspective view illustrating an ink jet recording apparatus according to an embodiment of the present invention. 3 is a flowchart for explaining a first embodiment of a double-sided printing control method in the ink jet recording apparatus according to the embodiment of the present invention. It is the table | surface which put together the threshold value of the printing rate. It is a figure which shows the warning display displayed on the touchscreen of the inkjet recording device of embodiment of this invention, or the monitor of an external apparatus. It is a figure for demonstrating 1st Embodiment of the correction method of the image information in the inkjet recording device of embodiment of this invention. 6 is a graph showing a correlation between a printing rate and a deformation amount of a sheet. 5 is a flowchart for explaining a paper discharge control method in the ink jet recording apparatus according to the embodiment of the present invention. It is a flowchart for demonstrating 2nd Embodiment of the control method of double-sided printing in the inkjet recording device of embodiment of this invention. It is a figure which shows the warning display displayed on the touchscreen of the inkjet recording device of embodiment of this invention, or the monitor of an external apparatus. It is a figure for demonstrating 2nd Embodiment of the correction method of the image information in the inkjet recording device of embodiment of this invention.

Explanation of symbols

12 Inkjet recording device (droplet ejection device)
28 Conveying belt (conveying means)
32 Inkjet recording head (droplet ejection head)
50 Conveying roller pair (reversing means)
52 Transport path switching guide (reversing means)
54 Drive mechanism (reversing means)
56 Transport path switching guide (reversing means)
58 Drive mechanism (reversing means)
60 motor (reversing means)
62 Paper discharge control unit (paper discharge control means)
100 Head drive unit (head control means)
106 Image information correction unit (image information correction)
108 Touch panel (correction notification means, selection notification means, selection means)
112 Drive permission control unit (drive permission control means)
114 Paper determination unit (sheet determination means)
122 External device (correction notification means, selection notification means, selection means)
P Paper (sheet)

Claims (9)

Conveying means for conveying the sheet;
A droplet discharge head for discharging and printing droplets on a sheet conveyed by the conveying means;
Reversing means for reversing the front and back of the sheet printed on the surface by the droplet discharge head and transporting the transport means upstream in the transport direction;
Head control means for controlling the driving of the droplet discharge head according to image information;
A droplet discharge device comprising:
And a first image information correction unit configured to reduce the surface printing amount to a predetermined value or less and transmit it to the head control unit when the printing amount on the front side of the received image information of the front and back double-sided printing is higher than a predetermined value. A droplet discharge device. A sheet determining means for determining the type of the sheet;
2. The first image information correction unit, when the sheet type determined by the sheet determination unit is a predetermined type, transmits the image information to the head control unit without correcting the image information. The droplet discharge device according to 1. Conveying means for conveying the sheet;
A droplet discharge head for discharging and printing droplets on a sheet conveyed by the conveying means;
Reversing means for reversing the front and back of the sheet printed on the surface by the droplet discharge head and transporting the transport means upstream in the transport direction;
Head control means for controlling the driving of the droplet discharge head according to image information;
A droplet discharge device comprising:
When the front side and the back side of the received image information of the front and back double-sided printing has a higher printing amount on the front side, the image information of the front side and the back side is replaced and transmitted to the head control unit. A droplet discharge apparatus characterized by the above. A paper discharge control means for controlling the driving of the reversing means,
The paper discharge control means drives the reversing means so that when printing is performed on the sheet according to the image information corrected by the second image information correction means, the sheet is reversed and discharged. The droplet discharge device according to claim 3, wherein the droplet discharge device is controlled. A sheet determining means for determining the type of the sheet;
4. The second image information correcting unit, when the sheet type determined by the sheet determining unit is a predetermined type, transmits the image information to the head control unit without correcting the image information. Or the droplet discharge apparatus of 4. Conveying means for conveying the sheet;
A droplet discharge head for discharging and printing droplets on a sheet conveyed by the conveying means;
Reversing means for reversing the front and back of the sheet printed on the surface by the droplet discharge head and transporting the transport means upstream in the transport direction;
Head control means for controlling the driving of the droplet discharge head according to image information;
A droplet discharge device comprising:
A droplet having a third image information correcting means for rotating the image information by 180 degrees and transmitting it to the head control means when the first half and the latter half of the received image information have a higher printing amount. Discharge device. A sheet determining means for determining the type of the sheet;
7. The third image information correcting unit, when the sheet type determined by the sheet determining unit is a predetermined type, transmits the image information to the head control unit without correcting the image information. The droplet discharge device according to 1.   The liquid droplet ejection apparatus according to claim 1, further comprising a correction notification unit that notifies the user that the image processing is corrected and the printing process is executed. A selection notifying means for notifying a user of selecting permission / non-permission of printing processing to be performed by correcting image information;
A selection means for allowing the user to select permission / non-permission of printing processing to be executed by correcting the image information;
Drive permission control means for controlling permission / non-permission of driving of the droplet discharge head according to the result selected by the selection means;
The droplet discharge device according to claim 1, wherein

Images