JP2008230861A - Inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent degradation of image quality caused by the friction of an image immediately after printing. <P>SOLUTION: This inkjet recording device is provided with a conveying roller 21 and a conveying belt 23 which turn over a paper sheet 3 and convey it toward a recording head 14. Printing on one surface of the paper sheet 3 is performed while conveying the paper sheet 3 fed from a paper feeding tray 4 toward the recording head 14 by the conveying roller 21, a part of the paper sheet 3 printed on one surface is temporarily discharged with the printed surface faced up, and a state of holding the paper sheet 3 is maintained for a predetermined time. After the predetermined time elapses, the paper sheet 3 is again fed to the conveying roller 21 for printing on the other surface, and the paper sheet 3 is discharged after printing on the other surface of the paper sheet 3 while conveying the paper sheet 3 again fed toward the recording head 14 by the conveying roller 21. A reversing passage where the conveying roller 21 turns over the paper sheet 3 fed from a paper feeding roller 26 and conveys it toward the recording head 14 and a reversing passage where the conveying roller 21 conveys the paper sheet 3 again fed toward the recording head 14 partially overlap with each other on a side upstream of the recording head 14. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inkjet recording apparatus, and more particularly to an inkjet recording apparatus capable of duplex printing (double-sided recording).

In an ink jet recording apparatus used as an image recording apparatus such as a printer or a copying apparatus, image information is recorded on a recording sheet in a recording apparatus as described in Patent Document 1, assuming that double-sided printing is possible. A first recording unit and a second recording unit disposed above the first recording unit are provided. The first recording unit includes a first recording unit, and the second recording unit includes a second recording unit. A first sheet feeding unit that feeds the recording sheet to the first recording unit, and a recording sheet that has been fed to the first recording unit and finished recording is conveyed to the second recording unit A recording paper transporting means, a second paper feeding means for feeding the recording paper to the second recording section, and a recording paper discharging means for discharging the recording paper transported to the second recording section There is.
JP-A-8-337011

  In this recording apparatus, when printing on both sides of the recording sheet, the recording sheet is fed from the first sheet feeding unit to the first recording unit, and the first recording unit applies the recording sheet to one side of the recording sheet. The recording paper that has been recorded and recorded on one side is fed to the upper second recording section by the recording paper conveying means while being guided by the guide member, and recorded on the other side of the recording paper by the second recording means. After that, the recording paper is discharged out of the apparatus main body by the recording paper discharging means.

  However, as described above, in an ink jet recording apparatus that performs double-sided printing by transporting recording paper from the first recording unit to the second recording unit in the recording apparatus main body, a plurality of recording units are included in the apparatus. Since it must be arranged, the structure becomes complicated, the apparatus becomes large, and the cost increases. In addition, the first and second recording units are arranged one above the other so that when the recording sheet is conveyed from the lower first recording unit to the upper second recording unit, the printing surface is printed by the guide member. However, in the case of ink jet recording, since it takes time to dry the ink, the image quality deteriorates when the image immediately after printing is rubbed.

  SUMMARY An advantage of some aspects of the invention is that it provides an ink jet recording apparatus capable of performing double-sided printing with stable image quality and reduced size.

In order to solve the above problems, an ink jet recording apparatus according to the present invention includes:
A paper feed tray provided at a lower portion of the apparatus main body for stacking paper;
An inkjet head mounted with the ink droplet ejection direction facing downward;
Paper feeding means for feeding the paper stacked in the paper feeding tray;
Conveying means for reversing the paper and conveying one side of the paper to face the inkjet head,
By conveying the paper fed from the paper feed tray by the transport means while facing the ink jet head, by ejecting ink droplets downward from the ink jet head, printing is performed on one side of the paper,
A part of the paper printed on one side by the inkjet head is discharged once with the printed side up, and the state where the paper is sandwiched with the printed side up is maintained for a predetermined time. When the predetermined time has elapsed, the paper is re-feeded to the transport means for printing on the other side,
The transporting means ejects ink droplets downward from the inkjet head while reversing the re-feeded sheet and transporting it opposite the inkjet head, thereby printing on the other surface of the sheet. Eject the paper,
A reversing path for reversing the paper fed from the paper feeding means by the transporting means and transporting the paper opposite to the ink jet head, and reversing the paper re-feeded by the transporting means for the ink jet A part of the reversing path that is conveyed facing the head overlaps with the upstream side of the inkjet head in the sheet conveying direction.

  According to the ink jet recording apparatus of the present invention, a part of the paper printed on one side by the ink jet head is discharged once with the printed side up, and the state where the paper is sandwiched is maintained for a predetermined time. When a predetermined time has elapsed, the paper is re-fed to the transport means for printing on the other side, and the paper fed from the paper feed means by the transport means is reversed to face the inkjet head The reversing path for transporting the paper and the reversing path for transporting the paper re-feeded by the transport means so as to face the ink jet head overlap with each other on the upstream side of the paper transport direction of the ink jet head. Therefore, it is possible to perform double-sided printing while suppressing the rubbing of the printing surface, improving the printing quality, and reducing the size of the apparatus.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is a perspective view showing an example of an ink jet recording apparatus according to the present invention, FIG. 2 is a perspective view of the recording apparatus as viewed from the back side, FIG. 3 is a configuration diagram of the recording apparatus, and FIG. 4 is an explanation of the recording apparatus. FIG.

  The ink jet recording apparatus includes a carriage that is movable in the main scanning direction inside the recording apparatus main body 1, a recording head that includes an ink jet head mounted on the carriage, an ink cartridge that supplies ink to the recording head, and the like. 2 and the like, and a sheet feeding cassette (or a sheet feeding tray) 4 which is a sheet feeding means capable of stacking a large number of sheets 3 from the front side is detachably attached to the lower part of the apparatus main body 1. In addition, a manual feed tray 5 can be freely opened and closed on the front side, the paper fed from the paper feed cassette 4 or the paper 3 set in the manual feed tray 5 is taken in, and the printing mechanism unit 2 takes the required After the image is recorded, it is discharged to a discharge tray 6 mounted on the rear side. An upper cover 7 is attached to the upper part so as to be opened and closed.

  The printing mechanism unit 2 holds a carriage 13 slidably in a main scanning direction (perpendicular to the paper in FIG. 3) by a main guide rod 11 and a sub guide rod 12 which are horizontally mounted on left and right side plates (not shown). On the lower surface side of 13, a recording head 14 composed of an inkjet head having nozzles for discharging ink droplets of yellow (Y), cyan (C), magenta (M), and black (Bk) is disposed in the ink droplet discharge direction downward. Each ink tank (ink cartridge) 15 for supplying ink of each color to the recording head 14 is replaceably mounted on the upper side of the carriage 5.

  The recording head 14 may be one in which a plurality of heads that eject ink droplets of each color are arranged in the main scanning direction, or one that has a nozzle that ejects ink droplets of each color. But you can. Further, the ink cartridge 15 is held on the carriage 13 by the cartridge pressing lever 16.

On the other hand, in order to convey the sheet 3 in the sub-scanning direction with respect to the printing position by the recording head 14, a conveyance belt 23 that conveys the sheet 3 by electrostatic adsorption between the conveyance roller 21 and the conveyance driven roller 22 is provided. A printing receiving member 24 is provided at a position facing the recording head 14 with the conveying belt 23 interposed therebetween. The conveying roller 21 preferably has a diameter that ensures sheet adhesion at the time of double-sided printing and does not separate the curvature, for example, 30φ or more, and the conveying belt 23 has a volume resistance of 10 ⁹ Ωcm to 10 ¹² Ωcm. It is preferable to use a medium resistor. Further, a front end roller 25 that defines the feed angle of the paper 3 is pressed against the transport roller 21 via the transport belt 23.

  On the other hand, in order to feed the paper 3 from the paper feed cassette 4 onto the transport belt 23, the paper feed roller 26 and the friction pad 27 for feeding the paper 3 separately one by one and the paper 3 to be fed are transported. A guide member 29 is provided for guiding to an intermediate roller 28 disposed in contact with the roller 21. The paper feed cassette 4 has a bottom plate 32 in the cassette body 31 and an extended bottom portion 33 that forms a paper placement surface together with the bottom plate 32. By changing the mounting position of the extended bottom portion 33 as shown in FIG. The length of the placement surface can be selected, and a large size paper exceeding the cassette body 31 can be used. Further, an end fence 34 for restricting the rear end of the sheet is attached to the extended bottom portion 33 so as to be movable in the length direction without any step.

  Further, in order to feed the paper 3 from the manual feed tray 5 to the transport belt 23, a pickup roller 35 that picks up the paper 3 from the manual feed tray 5, a feed roller 36 that feeds the paper 3, a feed roller 37, and the paper 3 And a guide member 38 for guiding the roller to the intermediate roller 28.

  Then, in order to discharge the printed paper 3 to the paper discharge tray 6, a guide member 41 that guides the paper 3, a paper discharge roller 42 that sends the paper 3 to the paper discharge tray 6, and a paper discharge follower roller 43. Is provided. The paper discharge tray 6 can be extended as shown by a virtual line in FIG.

  Further, the paper 3 that has passed the printing position by the recording head 4 is discharged in order to discharge the paper 3 that has been printed out of the apparatus body 1 and then feed it again to the transport belt 23 to perform double-sided printing. A guide member 45 is provided between the paper tray 6 and the paper feed cassette 4 so as to be inclined obliquely downward. A discharge path for the paper 3 is provided near the entrance of the guide member 45 and the guide member 41 on the paper discharge side. A first branching claw 46 for branching is provided to be swingable.

  Further, near the end of the guide member 45, the sheet 3 is placed on the upper surface of the sheet feeding cassette 4 outside the apparatus body 1 (this is the position where the sheet waits for refeeding, that is, the duplex printing sheet waiting position). ) And a switchback roller 47 and a switchback driven roller 48 for feeding the paper 3 into the apparatus main body 1 again. The switchback roller 47 is rotated forward when the paper 3 on which printing on one side has been completed is conveyed in the discharge direction, is reversed when the paper 3 is fed again, and is discharged when the paper 3 is discharged. It is stopped at a predetermined timing in order to pinch the rear end.

  Further, on the upstream side of the switchback roller 47 and the switchback driven roller 48 in the sheet discharge direction, the sheet 3 conveyance path is a discharge path to the outside of the apparatus body 1 and a path for refeeding the sheet 3 into the apparatus body 1 again. A second branching claw 49 for switching between the two is provided so as to be swingable, and the sheet 3 is guided in order to feed the sheet 3 fed into the apparatus main body 1 by the reverse rotation of the switchback roller 47 to the conveying belt 23. A guide member 51 for conveying, a double-sided relay roller 52 and a double-sided relay roller driven roller 53 for conveying the paper 3, and a conveyance roller driven roller 54 for feeding the paper 3 to the intermediate roller 28 following the conveyance roller 21.

Next, an outline of the control unit of the ink jet recording apparatus will be described with reference to FIG.
The control unit includes a microcomputer (hereinafter referred to as “CPU”) 80 that controls the entire recording apparatus, a ROM 81 that stores necessary fixed information, a RAM 82 that is used as a working memory, and image information. An image memory 83 for storing processed data, a parallel input / output (PIO) port 84, an input buffer 85, a gate array (GA) or parallel input / output (PIO) port 86, a head drive circuit 88 and a driver 89, 90 grade.

  Here, in addition to image information from the host side, the PIO port 84 includes information indicating whether or not double-sided printing is performed, information indicating the type of paper, various instruction information from an operation panel (not shown), and the home position of the carriage 13. Signals from various sensors such as a home position sensor for detecting (reference position) are input, and necessary information is sent to the host side and the operation panel side via the PIO port 84.

  Further, the head drive circuit 88 is based on various data and signals given through the PIO port 86, and generates energy generating elements (electromechanical conversion elements such as piezoelectric elements or the like) corresponding to the respective nozzles of the recording head (inkjet head) 6. A drive waveform is applied to an energy generating element of a drive nozzle (nozzle for ejecting ink droplets) corresponding to image information in an electrothermal conversion element such as a heating resistor. In addition, as a drive waveform, shapes, such as a rectangular pulse, a triangular waveform, and other sine (sine) waveforms, can be used.

  Further, the driver 89 includes a motor 91 that scans the carriage 13 in the main scanning direction in accordance with driving data supplied via the PIO port 86, a motor 92 that rotates the transport roller 21 in the paper transport direction (sub-scanning direction), and a switch. The motor 93 that rotates the back roller 47 is driven and controlled. The driver 90 drives and controls solenoids 94 and 95 that swing the first branch claw 46 and the second branch claw 49, respectively.

Next, the operation of the thus configured ink jet recording apparatus will be described with reference to FIGS.
Referring to FIG. 6, when double-sided printing is instructed, the first branch claw 46 is switched to the double-sided printing side, the second branch claw 49 is switched to the discharge side, as shown in FIG. Is rotated forward (rotates in the direction to eject the paper out of the apparatus). Further, by rotating the sheet feeding roller 26 to feed the sheet 3 from the sheet feeding cassette 4, the sheet 3 is sent to the conveying belt 23 of the conveying roller 21 and is electrostatically attracted to the conveying belt 23 to perform sub-scanning. Here, the energy generating element of the recording head 14 is driven according to the recorded image while moving the carriage 13 in the main scanning direction, so that a required image is printed on one side of the sheet 3.

  Here, since the first branching claw 46 is switched to the double-sided printing side of the paper 3 that has been printed by the recording head 14, it is guided between the switchback roller 47 and the switchback driven roller 48 by the guide member 45. , Transported by the switchback roller 47 and the switchback driven roller 48, and discharged out of the apparatus main body 1 as shown in FIG. At this time, the switchback roller 47 is stopped at the timing when the rear end portion of the sheet 3 is positioned between the switchback roller 47 and the switchback driven roller 48, and the end portion of the sheet 3 is sandwiched as shown in FIG. maintain.

  Here, it is determined whether or not a predetermined time has elapsed after the one-side printing on the sheet 3 is completed. This predetermined time is set to the time required for the ink droplets that have landed on the paper 3 to dry. Therefore, there is no need to wait for the elapse of a predetermined time when it takes no time to dry the ink droplets, and when the predetermined time is set, other processing can be performed during that time. The predetermined time can be changed according to the ink droplet amount. The ink droplet amount can be determined by counting the number of black (including color) dots in the image data.

  Then, when a predetermined time has elapsed after completion of the single-sided printing on the paper 3, the first branch claw 46 is switched to the paper discharge side and the second branch claw 49 is switched to the refeed side as shown in FIG. Thereafter, the switchback roller 47 is rotated in the reverse direction and the intermediate roller 51 is driven, so that the guide member 51 guides the sheet 3 that has nipped the end portion between the switchback roller 47 and the switchback driven roller 48. The paper is fed again to the transport belt 23 by the roller 51. In this case, the paper feed linear speed when the paper 3 is fed again is set to be substantially the same as the linear speed of the transport belt 23. Thus, the paper 3 can be fed while being in close contact with the transport belt 23 in a state where the printing surface is not rubbed against the transport belt 23.

  The sheet 23 re-feeded in this manner is conveyed by the conveying belt 23, the image is recorded on the other side by the recording head 14, and the sheet 3 on which the printing by the recording head 14 is finished is the first branching claw 46. Then, the paper is guided by the guide member 41 on the paper discharge side, conveyed between the paper discharge roller 42 and the paper discharge roller 43, and discharged onto the paper discharge tray 6.

  In this way, after printing on one side of the paper, an open system that once discharges at least a part of the paper to the outside of the apparatus main body requires only one recording head (recording means), and the configuration inside the apparatus main body. In addition, the ink droplet drying time for double-sided printing can be increased, and the printing quality can be improved. In this case, by discharging the printing surface of the paper out of the apparatus main body, the printing surface on which the ink droplets are attached can be dried out of the apparatus main body, and the printing quality can be improved.

  In addition, by reversing and re-feeding the paper for double-sided printing with a switchback method, the configuration for performing double-sided printing becomes simple and other processing is performed while ensuring ink drying time. It can also be done. Furthermore, by discharging the paper below the printing position by the inkjet head for double-sided printing, it is possible to stably discharge the heavy paper with ink droplets to the double-sided printing standby position. it can. In this case, the duplex printing standby position is set on the upper surface of the sheet feeding means such as a sheet feeding tray or a sheet cassette for setting paper, so that it is not necessary to provide a separate dedicated tray for duplex printing. Becomes easier.

  Furthermore, by transporting the paper to the printing position with a transport means using a transport belt, it can be transported without rubbing the printing surface of the paper on which single-sided printing has been completed. By making the paper feed line speed approximately the same as the line speed of the conveyor belt, it is possible to re-feed without rubbing the printing surface on which the ink droplets adhere.

  In the above embodiment, the paper is discharged between the paper discharge tray and the paper feed unit. For example, in the recording apparatus in the above embodiment, the paper after the single-sided printing is finished is output to the paper discharge tray. The sheet can be discharged and the sheet discharge roller can be used as a switchback roller to re-feed the sheet from the sheet discharge tray.

  Further, in this ink jet recording apparatus, since the printing surface of the paper is discharged outside the apparatus main body, the ink droplets can be naturally dried outside the apparatus main body. Further, since the paper on which printing on one side has been completed is reversed and re-fed by the switchback method, the paper can be re-fed with a simple configuration. Furthermore, since the paper discharge position is lower than the printing position by the ink jet head, the paper with ink droplets attached thereto can be stably discharged to the double-sided printing standby position in a natural state.

  Further, since the sheet is discharged onto the upper surface of the sheet feeding means, a dedicated tray or the like for waiting for the sheet to perform sheet re-feeding after completion of single-sided printing becomes unnecessary, and the structure is simplified. Further, since the sheet is transported to the printing position by the transport means using the transport belt, it is possible to prevent the printed surface after the printing from being rubbed during double-sided printing.

  In addition, since the paper feed linear speed when re-feeding the paper is substantially the same as the linear speed of the conveyor belt, the printed surface after the printing is finished is not rubbed during double-sided printing. be able to. Furthermore, since one recording means using an inkjet head is provided, double-sided printing can be performed with a simple configuration.

The perspective view which shows an example of the inkjet recording device which concerns on this invention Perspective view of the same recording apparatus viewed from the back side Configuration diagram of the recording device Illustration of the recording device Schematic block diagram of the control unit of the recording apparatus Schematic flowchart for explaining the operation of the recording apparatus Explanatory diagram for explaining the same action Explanatory diagram for explaining the same action Explanatory diagram for explaining the same action

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main body 2 ... Printing mechanism part 3 ... Paper 4 ... Paper feed cassette 5 ... Manual feed tray 6 ... Paper discharge tray 13 ... Carriage 14 ... Recording head 21 ... Conveyance roller 23 ... Conveyance belt 42 ... Discharge roller 46 ... First 1 branch claw 47 ... switchback roller 49 ... 2nd branch claw 53 ... intermediate drive roller.

Claims (1)

A paper feed tray provided at a lower portion of the apparatus main body for stacking paper;
An inkjet head mounted with the ink droplet ejection direction facing downward;
Paper feeding means for feeding the paper stacked in the paper feeding tray;
Conveying means for reversing the paper and conveying one side of the paper to face the inkjet head,
By conveying the paper fed from the paper feed tray by the transport means while facing the ink jet head, by ejecting ink droplets downward from the ink jet head, printing is performed on one side of the paper,
A part of the paper printed on one side by the inkjet head is discharged once with the printed side up, and the state where the paper is sandwiched with the printed side up is maintained for a predetermined time. When the predetermined time has elapsed, the paper is re-feeded to the transport means for printing on the other side,
The transporting means ejects ink droplets downward from the inkjet head while reversing the re-feeded sheet and transporting it opposite the inkjet head, thereby printing on the other surface of the sheet. Eject the paper,
A reversing path for reversing the paper fed from the paper feeding means by the transporting means and transporting the paper opposite to the ink jet head, and reversing the paper re-feeded by the transporting means for the ink jet An inkjet recording apparatus, wherein a part of the reversing path that is conveyed opposite to the head overlaps on the upstream side in the sheet conveying direction of the inkjet head.

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