JP4533769B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus capable of performing duplex printing on a recording medium.

  In an image forming apparatus such as a printer, a facsimile machine, a copier, and a multi-function machine having at least two of these functions, a recording head (image forming means) constituted by a droplet discharge head for discharging ink droplets is used. There is a so-called inkjet recording apparatus that forms an image by adhering ink droplets to a recording medium while conveying the recording medium such as recording paper. As a droplet discharge head in this ink jet recording apparatus, a piezoelectric type using an electromechanical conversion element such as a piezoelectric element, or an ink film boiling using an electrothermal conversion element such as a heating resistor disposed in the discharge. There are a thermal type that discharges ink droplets by generating bubbles, and an electrostatic type that discharges ink droplets by deforming a diaphragm that forms the wall surface of the discharge chamber with an electrostatic force.

  In addition, as an ink jet recording apparatus, a shuttle (serial) type that records a recording medium by scanning the liquid droplet ejection head in a direction orthogonal to the conveyance direction, and a direction in which the liquid droplet ejection head conveys the recording medium. There is a full-line type that is fixedly arranged in a line shape in a direction perpendicular to the line and recorded.

JP-A-6-71956 JP 2001-063019 A

  In such an ink jet recording apparatus, as described in Patent Document 1, it is possible to perform double-sided printing (double-sided printing and double-sided recording are also used synonymously) on a recording medium. A reversing tray for feeding and reversing recording paper is provided in addition to the paper ejection tray so that the recording medium on which image formation has been performed is discharged to the reversing tray and then fed again from the reversing tray. There is what I did.

  Further, as described in Patent Document 2, after a part of a recording medium on which an image has been formed is held by a paper discharge roller and discharged to a paper discharge tray, the paper discharge roller is reversed and the apparatus is again operated. There is something that is re-feeded by taking it inside.

  By the way, in the ink jet recording apparatus, in order to reduce the size, which is one of the advantages, the transport for feeding the recording medium to the recording unit (image forming unit) by the recording head, the position facing the recording head. One drive source performs sub-scan feed for transporting the recording medium, transport for discharging the recorded recording medium, switchback transport for duplex printing, transport for refeeding, and the like. I have to.

  For this reason, in the ink jet recording apparatuses disclosed in Patent Documents 1 and 2 described above, the recording medium on which image formation has been performed is sent out to the reversing tray or the paper discharge tray by the forward rotation of the platen roller or the conveyor belt. After that, the platen roller and the conveyor belt are reversed so that the recording medium is switched back and conveyed to the paper feeding side, and the platen roller and the conveyor belt are rotated forward again to perform recording on the other side.

  In this case, in ink-jet recording, it takes a certain amount of time to dry the ink, so that there is a problem that the image quality deteriorates when the image immediately after printing is rubbed. Therefore, as described above, there is an advantage that the drying time can be ensured by repeating forward rotation, reverse rotation, and forward rotation by one drive source.

  However, regardless of personal use, when it becomes an image forming apparatus for business use, the double-sided printing function as described above has poor productivity for double-sided printing and is not practical. Therefore, there is a demand for an image forming apparatus capable of improving the quality by securing the ink drying time, which is a problem peculiar to inkjet recording, while improving the productivity of double-sided printing.

  The present invention has been made in view of the above problems, and an object thereof is to provide an image forming apparatus capable of significantly improving the productivity of double-sided printing while reducing the size of the apparatus.

In order to solve the above-described problems, the present invention includes an image forming unit that forms an image on a recording medium and a paper feeding unit that feeds the recording medium disposed below the image forming unit. In the image forming apparatus, the image forming unit includes a recording head that forms an image by ejecting droplets onto the recording medium, and a carriage that mounts the recording head and moves the recording head in the main scanning direction. Conveying means for intermittently conveying the recording medium to the recording head, the paper feeding unit separating and feeding a plurality of the recording media placed thereon, and A registration motor provided on the front side in the conveyance direction of the image forming unit and against which the recording medium is abutted; a driving motor that intermittently drives the conveyance unit; and the paper feeding roller and the registration roller Drive through Each of the sheet feeding motors is provided, and when the recording medium straddles the registration roller and the conveying unit of the sheet feeding unit during image formation, the clutch of the registration roller is turned off to turn off the image. An image forming apparatus is characterized in that the recording medium is intermittently conveyed by the conveying means of the forming unit.

In the present invention , a transport roller downstream of the image forming unit in the transport direction, a paper discharge roller for performing reverse paper discharge on a paper discharge tray, and a paper discharge motor for driving the transport roller and the paper discharge roller are provided. It is effective that the paper discharge unit is further provided, and the paper discharge motor is intermittently driven in synchronization with the transport unit .

According to the present invention, even if the recording medium straddles the registration roller and the conveying unit of the image forming unit, the intermittent conveyance of the conveying unit can be performed without any trouble if the clutch of the registration roller is turned off.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram showing an overall configuration of an ink jet recording apparatus which is an embodiment of an image forming apparatus according to the present invention.

  The image forming apparatus includes an image forming unit 2 for forming an image inside the apparatus main body 1, and the image forming unit 2 is provided with a conveying belt 3 and a sheet 5 that convey a sheet as a recording medium in the sub-scanning direction. It has a recording head 4 for forming an image. Although not shown, the recording head 4 of the present embodiment includes a plurality of line-type droplet discharge heads arranged side by side along the conveyance direction of the paper 5 and includes at least four droplets that discharge droplets of different colors. ing. The recording head 4 is mounted on a carriage (not shown), moves the carriage in the main scanning direction, and ejects liquid droplets from the recording head 4 while feeding the paper 5 in the paper transport direction (sub-scanning direction). It is a shuttle type that forms. The recording head 4 uses a piezoelectric element as a pressure generating means (actuator means) for pressurizing the ink in the ink flow path (pressure generation chamber) to deform the diaphragm that forms the wall surface of the ink flow path. A so-called piezo type that discharges ink drops by changing the volume in the flow path, or a so-called discharge that discharges ink drops with a pressure generated by heating the ink in the ink flow path using a heating resistor to generate bubbles. The thermal type, the diaphragm that forms the wall surface of the ink flow path and the electrode are placed opposite to each other, and the diaphragm is deformed by the electrostatic force generated between the vibration plate and the electrode, thereby reducing the volume of the ink flow path. It is possible to use an electrostatic type that changes and discharges ink droplets.

Next, the flow of paper in the image forming apparatus will be described.
A main body paper feed unit 6 is provided below the image forming unit 2 of the apparatus main body 1, and when the paper feed roller 7 of the main body paper feed unit 6 is operated, the sheet 5 as a recording medium is prevented from being double fed (not shown). 1) are fed one by one. The fed paper 5 is abutted against and aligned with the registration roller 8 in front of the image forming unit, and then conveyed to the conveying belt 3. The conveyor belt 3 is an electrostatic attraction belt having an endless belt 3c wound around the belt wheels 3a and 3b, and the sheet 5 is conveyed by being electrostatically attracted to the belt 3c. An image is formed by the recording head 4 during conveyance.

  The sheet 5 on which image formation has been completed is conveyed to the branching claw 13 by the conveying rollers 10, 11, and 12. The branching claw 13 can be switched between a position indicated by a solid line and a position indicated by a dotted line, and the branching claw 13 has a solid line. The paper 5 is reversely discharged to a paper discharge unit 16 provided on the upper portion of the apparatus main body 1 via a transport roller 14 and a paper discharge roller 15. When the duplex mode is selected, the branch claw 13 is switched to the dotted line position, and the sheet 5 on which one side is printed is sent to the duplex unit 20 as the duplex device via the duplex relay rollers 17 and 18. The double-sided unit 20 can be arranged in advance in the apparatus. However, the double-sided unit 20 is arranged at the lower part of the main body paper feeding unit 6 so as to select whether or not to be installed. It can also be configured as an optional unit.

  The sheet 5 conveyed to the duplex unit 20 is conveyed in the unit by the duplex rollers 21 to 26 and is sent to the switchback conveyance path 27. When the sheet 5 is transported by the reversing rollers 28 and 29 in the switchback transport path 27 and the paper 5 is accommodated in the switchback transport path 27, the reversing rollers 28 and 29 are driven in reverse and the rear end of the paper 5 becomes the leading end, so The sheet is fed again toward the image forming unit 2 through a double-sided exit roller 30 as a member.

  In the image forming apparatus according to the present embodiment, the additional sheet feeding unit 40 can be selectively attached to the lower part of the duplex unit 20. The additional sheet feeding unit 40 of this example is configured by arranging two upper and lower sheet feeding cassettes 41 and 42. However, the additional sheet feeding unit 40 may have only one sheet feeding cassette, and further three units. It may be arranged as described above. When the additional sheet feeding unit 40 is attached, the sheet 5 fed from the additional sheet feeding unit 40 is transported to the image forming unit through the duplex unit 20 because it is disposed below the duplex unit 20. Yes. That is, the sheet 5 fed from the additional sheet feeding unit 40 joins the refeed conveyance path 31 in the duplex unit 20 and is conveyed toward the image forming unit 2 by the duplex exit roller 30. Reference numeral 43 denotes a paper feeding roller of the additional paper feeding unit, and 44 denotes a guide roller of the additional paper feeding unit.

  As described above, when the additional paper feeding unit 40 is provided in the lower part of the duplex unit 20, the paper 5 fed from the additional paper feeding unit 40 is conveyed to the image forming unit without passing through the duplex unit 20. Further, it is necessary to provide a transport route from the additional sheet feeding unit 40 to the image forming unit on the side of the apparatus, and the apparatus width increases accordingly. In that respect, in the present invention, since the sheet 5 fed from the additional sheet feeding unit 40 passes through the duplex unit 20, such a problem does not occur. In FIG. 2, a roller with (CL) after the reference sign indicates a roller that is turned on / off by an electromagnetic clutch, and a roller with (1 way) after the reference sign indicates a roller that is driven via a one-way clutch. A roller with (intermittent) after the symbol indicates a roller driven intermittently.

FIG. 2 is an explanatory diagram showing the image forming apparatus shown in FIG. 1 with the rollers driven for each drive motor divided by hatching or the like.
In FIG. 2, the image forming apparatus of this embodiment includes a total of six motors: a paper feed motor, a belt motor, a paper discharge motor, a double-sided motor, a refeed motor, and an additional paper feed motor. Rollers driven by the paper feed motor are a paper feed roller 7, a registration roller 8, a manual paper feed roller 19, and a guide roller 9 for paper fed from the duplex unit 20. The belt motor drives the belt by rotating one of the belt wheels 3a and 3b. The paper discharge motor rotationally drives the transport rollers 10, 11, 12, and 14, the paper discharge roller 15, and the double-side relay rollers 17 and 18. Since the present embodiment is an ink jet recording apparatus, the conveyance belt 3 during printing is intermittently driven, and the sheet feeding roller 7, the registration roller 8, the manual sheet feeding roller 19 and the guide roller 9 driven by the sheet feeding motor are as follows. It is driven via an electromagnetic clutch (not shown). As a result, even if the sheet 5 straddles the registration roller 8 and the conveyance belt 3, if the clutch of the registration roller 8 is turned off, the intermittent conveyance of the conveyance belt 3 can be performed without any trouble. Further, the transport rollers 10, 11, 12, 14 and the discharge roller 15 that are rotationally driven by the paper discharge motor can be intermittently driven in synchronization with the transport belt 3, whereby the paper 5 is transported to the transport belt 3 and the transport roller. Intermittent driving can be performed without any trouble even in a state where it is over 10 or more.

  The double-sided motor drives the double-sided conveyance rollers 21 to 26, and the refeed motor drives the reversing rollers 28 and 29 and the double-sided exit roller 30. The additional paper feed motor rotates the paper feed roller 43 and the guide roller 44.

  In FIGS. 1 and 2, all the arrows shown in the paper conveyance path are paper detection sensors. In the apparatus main body 1, a registration sensor S1, a printing unit inlet sensor S2, an image registration sensor S3, a printing unit outlet sensor S4, a branch sensor S5, a paper discharge sensor S6, and an option sensor 7 are provided. Further, the duplex unit 20 is provided with a duplex entrance vertical transport sensor S8, a standby sensor S9, a reverse sensor S10, and a duplex exit vertical transport sensor S11. Further, the extension paper feed unit 40 is provided with an extension bank vertical conveyance sensor S12. By controlling on / off of the motor and on / off of the clutch from the signals of these sensors, the image forming apparatus can be operated efficiently, and each sensor can detect a paper jam.

  The image forming apparatus configured as described above can achieve high productivity by interleafing, that is, by feeding the next sheet and printing sequentially before the previous sheet is discharged.

Next, an example of achieving high productivity when a plurality of double-sided prints are obtained from the additional paper supply unit 40 by interleaf will be described with reference to the timing chart of FIG.
For the first sheet feeding, the additional sheet feeding roller 43 is driven to feed the sheet 5 as usual. The fed sheet 5 is the guide roller 44, the duplex exit roller 30 of the duplex unit 20, and the apparatus main body 1. After being abutted against and aligned with the registration roller 8 via the vertical conveyance roller 19, the registration roller is driven and sent to the conveyance belt 3.

  When printing on the paper 5 is completed, the paper is conveyed toward the duplex unit 20 by switching the branching claw 13 to the dotted line position. During the printing of the first sheet, the second sheet is fed from the additional sheet feeding unit 40 and printed so as to be substantially continuous, and is sent to the duplex unit 20. Then, the first sheet is sent to the duplex waiting 1 which is the switchback path 27 of the duplex unit 20, and the second sheet is sandwiched between the duplex transport rollers before the switchback path 27 of the duplex unit 20. 3, the third sheet is fed from the additional sheet feeding unit 40. The sheet 5 is also abutted against the registration roller 8 via the duplex exit roller 30 of the duplex unit 20 and the vertical conveying roller 19 of the apparatus body 1. At this time, the re-feed motor is driven to rotate the double-sided exit roller 30, but the reversing rollers 28 and 29 are driven by the re-feed motor via the clutch, and the clutch is turned off to stand by on the switchback path. The paper being transported is not conveyed.

  When the third sheet is printed, the first sheet waiting in the switchback path 27 is fed again. At this time, the second sheet that is also waiting in the duplex unit 20 is not moved because the duplex transport rollers 21 to 26 are driven by the duplex motor instead of the refeed motor. .

  As described above, in the image forming apparatus of the present invention, the additional sheet feeding unit 40 is provided below the duplex unit 20, and the sheet 5 fed from the additional sheet feeding unit 40 passes through the duplex unit 20 and is conveyed to the image forming unit 2. Even when configured to do so, the third sheet can be fed from the additional sheet feeding unit 40 and printed when the duplex unit 20 is waiting for the sheet (two sheets) printed on one side. The productivity of double-sided printing can be greatly improved.

1 is a schematic configuration diagram illustrating an overall configuration of an inkjet recording apparatus that is an embodiment of an image forming apparatus according to the present invention. FIG. 2 is an explanatory diagram illustrating the image forming apparatus illustrated in FIG. 1 in which rollers driven for each drive motor are divided by hatching or the like. 6 is a timing chart showing an example of achieving high productivity when a plurality of double-sided prints are obtained from an additional paper feeding unit by interleaf.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Image formation part 3 Conveyor belt 5 Paper 6 Main body paper feed part 20 Duplex unit 27 Switchback part 30 Double-sided exit roller 40 Additional paper feed part

Claims (2)

An image forming apparatus having an image forming unit that forms an image on a recording medium and a paper feeding unit that feeds a recording medium arranged below the image forming unit in the apparatus main body.
The image forming unit includes a recording head that forms an image by discharging droplets to the recording medium, a carriage that mounts the recording head and moves the recording head in a main scanning direction, and a recording head. A conveying means for intermittently conveying the recording medium,
The paper feed unit includes a paper feed roller that separates and feeds a plurality of the recording media placed thereon, and a registration roller that is provided on the front side in the transport direction of the image forming unit and against which the recording medium is abutted. Have
A driving motor that intermittently drives the conveying means, and a paper feeding motor that drives the paper feeding roller and the registration roller via a clutch, respectively.
When the recording medium straddles the registration roller and the conveying unit of the paper feeding unit at the time of image formation, the recording medium is intermittently moved by the conveying unit of the image forming unit by turning off the clutch of the registration roller. An image forming apparatus characterized in that the image forming apparatus conveys the image. A paper discharge unit further comprising a transport roller downstream of the image forming unit in the transport direction, a paper discharge roller for reverse paper discharge to a paper discharge tray, and a paper discharge motor for driving the transport roller and the paper discharge roller; The image forming apparatus according to claim 1 , wherein the paper discharge unit intermittently drives the paper discharge motor in synchronization with the transport unit .

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