JP2013103457A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can record, without enlarging the size thereof, an image on a recording medium by an inkjet system at a position where the recording medium does not pass an image forming unit of an electrophotographic system.SOLUTION: The image forming apparatus includes: a first conveyance path for guiding the recording medium; a first image forming unit 99 for forming an image on the recording medium conveyed through the first conveyance path by an electrophotographic system; a second conveyance path for reversing the recording medium passed through the first conveyance path and guiding the recording medium back to the first conveyance path; a second image forming section 100 for forming an image by an inkjet system on the recording medium conveyed through the second conveyance path; and a moving mechanism for moving the second image forming unit 100 from a second recording position at which an image is formed on the recording medium conveyed through the second conveyance path to a first recording position at which an image is formed on the recording medium conveyed through the first conveyance path.

Description

  The present invention relates to an image forming apparatus having an electrophotographic image forming unit and an inkjet image forming unit.

  Conventionally, as a method for obtaining an image, there are mainly an electrophotographic method (toner type) method and an ink jet method (ink type) method. Each of these two methods (recording methods) has advantages. The electrophotographic method can increase the speed, and the ink-jet method is excellent in ink color reproducibility. There has been proposed an apparatus for forming an image by using these advantages.

  For example, Japanese Patent Application Laid-Open No. 2002-301838 achieves an apparatus for forming an image by using an ink-jet image forming unit after an electrophotographic image forming unit and using the advantages of each other.

JP 2002-301838 A

  However, in the conventional image forming apparatus, the conveyance path of the recording medium is a path that passes from the electrophotographic image forming unit to the ink jet image forming unit. Therefore, even if only an image by the ink jet method is formed, the recording medium passes through the electrophotographic image forming unit. Therefore, even when only an ink jet image is formed, since the recording medium passes through the electrophotographic image forming portion, the electrophotographic image forming portion is durablely deteriorated by the passage of the recording medium.

  For example, when the recording medium is special paper such as an envelope different from plain paper, there is a risk that wrinkles or the like may occur in the special paper as the recording medium due to the fixing unit in the electrophotographic image forming unit. Further, in the case of a small size paper that can be used as a recording medium, there is a possibility that the fixing unit in the electrophotographic image forming unit may be heated at a portion where the recording medium does not pass, and the fixing unit may be deteriorated.

  In addition, if either of the electrophotographic image forming unit or the inkjet image forming unit is used to perform double-sided image printing in accordance with the user's desired use such as printing on both sides of the recording medium, the apparatus becomes large. There is a problem of becoming.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus capable of recording by an ink jet image forming unit at a position where a recording medium does not pass through an electrophotographic image forming unit without increasing the size of the apparatus. is there.

  In order to achieve the above object, the present invention provides a first transport path for guiding a recording medium, and a first image forming section for forming an image by electrophotography on a recording medium transported through the first transport path. A second conveyance path for guiding the recording medium passing through the first conveyance path to the first conveyance path by reversing the front and back surfaces thereof, and the second conveyance path. A second image forming unit that forms an image on a recording medium by an inkjet method, and a second image forming unit from a second recording position that forms an image on a recording medium that is conveyed along the second conveyance path. And a moving mechanism for moving the first transport path to a first recording position for forming an image on the recording medium transported.

  According to the present invention, the inkjet image forming unit can be freely moved to the second recording position in the second conveying path and the first recording position in the first conveying path where the electrophotographic image forming unit is located. it can. For this reason, it is possible to select a recording position by an inkjet image forming unit in either case of forming an image on one side of the recording medium or forming an image on both sides of the recording medium. For example, it is possible to select a recording position at which the recording medium does not pass through the electrophotographic image forming unit as the recording position by the ink jet type image forming unit. As a result, when forming an image by the ink jet method, the recording medium and the first image forming unit of the electrophotographic method are deteriorated due to the recording medium passing through the first image forming unit of the electrophotographic method. Can be prevented.

  Further, an ink jet system capable of moving a recording position with respect to a first transport path for forming an image in an electrophotographic image forming unit or a second transport path for guiding a recording medium to the first transport path again. By providing the image forming unit, it is possible to reduce the size of the apparatus.

Schematic cross-sectional view of image forming apparatus Sectional view showing double-sided image formation by electrophotography Cross-sectional view showing single-sided image formation by inkjet method Sectional drawing showing the 1st surface printing method at the time of double-sided image formation by an inkjet system Sectional drawing showing the 2nd page printing method at the time of double-sided image formation by an inkjet system Top view schematic diagram illustrating the configuration of an inkjet image forming unit Cross-sectional operation explanatory diagram showing the operation of the inkjet image forming unit Flow chart for image formation Block diagram for image formation Sectional drawing showing the image formation of the 1st surface at the time of double-sided image formation by the inkjet system of 2nd Embodiment Sectional drawing showing the image formation of the 2nd surface at the time of double-sided image formation by the inkjet system of 2nd Embodiment Sectional drawing showing the discharge method of the 2nd surface at the time of double-sided image formation by the inkjet system of 2nd Embodiment

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the following embodiments should be changed as appropriate according to the configuration of the apparatus to which the present invention is applied and various conditions. It is not intended to limit the scope of the invention only to them.

[First Embodiment]
The image forming apparatus according to the first embodiment will be described with reference to FIGS. In the present embodiment, a color image forming apparatus using an electrophotographic system and an ink jet system is illustrated as an image forming apparatus.

  FIG. 1 is a schematic cross-sectional view illustrating a schematic configuration of the image forming apparatus according to the first embodiment. Here, the electrophotographic system employs an intermediate transfer tandem system in which four color image forming portions having different colors are arranged side by side under the intermediate transfer belt. On the other hand, in the ink jet system, a line system in which recording is performed by a linear recording unit provided in a direction orthogonal to the sheet conveying direction is adopted.

<Sheet transport process>
The recording medium S is stored in the form of being stacked in the recording medium storages 61 and 62, and is fed one by one by the feeding units 71 and 72 in accordance with the image forming timing. The recording medium S sent out by the feeding means 71 and 72 passes through the transport path 70. Thereafter, the switching member 105 guides either the transport path 121 constituting the first transport path or the transport path 131 for guiding the recording medium to the second transport path.

  The conveyance path 121 is a conveyance path for sending the recording medium S to the first image forming unit 99 that forms an image by electrophotography, and constitutes a first conveyance path for guiding the recording medium. The conveyance path 131 is a conveyance path that guides the recording medium to the second conveyance path for reversing the front and back surfaces of the recording medium that has passed through the first conveyance path and guiding the recording medium to the first conveyance path again. .

  The first transport path for guiding the recording medium is composed of transport paths 121 and 122. An electrophotographic first image forming unit 99 is located in the first transport path. A second transport path that reverses the front and back surfaces of the recording medium and guides it to the first transport path again includes transport paths 133, 132, and 111. An ink-jet second image forming unit 100 is located in the second transport path.

  Next, each of the electrophotographic method and the inkjet method will be described with respect to the image forming process.

<Image creation process by electrophotography>
The recording medium S guided toward the first image forming unit 99 by the switching member 105 is transported to the registration roller pair 73 through the transport path 121 constituting the first transport path. The registration roller pair 73 has a function of correcting the skew by causing the recording medium S conveyed from the recording medium storages 61 and 62 to abut and creating a loop to follow the leading end of the recording medium S. The registration roller pair 73 conveys the recording medium S to the secondary transfer unit at a predetermined timing in accordance with the timing of image formation on the recording medium S, that is, the toner image carried on the image carrier. It has a function.

  The registration roller pair 73 sends out the recording medium S to the secondary transfer portion at a desired timing after correcting skew feeding. The secondary transfer portion is a toner image transfer nip portion to the recording medium S formed by the opposing secondary transfer inner roller 32 and secondary transfer outer roller 41, and applies a predetermined pressure and electrostatic load bias. As a result, the toner image is transferred onto the recording medium S.

  Next, a process for forming an image sent to the secondary transfer unit at the same timing as the conveyance process of the recording medium S to the secondary transfer unit will be described.

  The electrophotographic image forming unit 99 mainly includes an image carrier and process means acting on the image carrier. Here, there are four sets of image forming units 99 of yellow (Y), magenta (M), cyan (C), and black (K). Of course, the number of colors is not limited to four, and the color arrangement order is not limited to this.

  Each image forming unit includes a photoconductor 11 (11Y, 11M, 11C, 11K) as an image carrier, a charging device 12 (12Y, 12M, 12C, 12K) as a process means, and an exposure device 13 (13Y, 13M, 13C). , 13K), developing device 14 (14Y, 14M, 14C, 14K), primary transfer device 35 (35Y, 35M, 35C, 35K), and photoconductor cleaner 15 (15Y, 15M, 15C, 15K). .

  The exposure device 13 is driven on the basis of the image information signal sent to the rotating photoconductor 11 whose surface is uniformly charged in advance by the charging device 12, and a latent image is formed. The electrostatic latent image formed on the photoconductor 11 is developed as a toner image on the photoconductor 11 through toner development by the developing device 14. Thereafter, a predetermined pressing force and an electrostatic load bias are applied by the primary transfer device 35, and the toner image is transferred onto the intermediate transfer belt 31. Thereafter, the transfer residual toner slightly remaining on the photoconductor 11 is collected by the photoconductor cleaner 15 to prepare for the next image formation again.

  Next, the intermediate transfer belt 31 will be described. The intermediate transfer belt 31 is stretched by rollers such as a drive roller 33, tension rollers 34 and 36, and a secondary transfer inner roller 32, and is conveyed and driven in the direction of arrow A in the figure. The image forming process of each color that is processed in parallel by the above-described Y, M, C, and K image forming units is performed at a timing of superimposing on the upstream color toner image primarily transferred onto the intermediate transfer belt 31. As a result, a full-color toner image is finally formed on the intermediate transfer belt 31 and conveyed to the secondary transfer unit.

  A full-color toner image is secondarily transferred from the intermediate transfer belt 31 onto the recording medium S in the secondary transfer portion, and then the recording medium S is conveyed to the fixing device 5. The fixing device 5 melts and fixes the toner image on the recording medium S by applying a predetermined pressing force by an opposing roller or belt or the like and generally a heating effect by a heat source such as a heater.

  The recording medium S on which the toner image is melted and fixed by the fixing device 5 is transported by the transport roller pair 74 through the transport path 122 constituting the first transport path. The conveyed recording medium S is stacked on the discharge tray 65 by the discharge roller pair 76.

  Further, from the viewpoint of energy saving, the image forming unit 100 using the ink jet method is configured not to operate while the image forming unit 99 using the electrophotographic method is forming an image. Control of this operation is performed by a controller (CPU) 90 as a control unit described later. At this time, the movable inkjet image forming unit 100 is positioned (moved) at a second recording position where an image can be formed on the recording medium conveyed along the second conveyance path. . Here, the second recording position is the initial position of the inkjet image forming unit 100.

<Electrophotographic process for creating double-sided images>
Next, a case where double-sided image formation is performed on the recording medium S by the electrophotographic method will be described with reference to FIG.

  The recording medium S on which the toner image is melted and fixed by the fixing device 5 passes through the transport path 122 and is transported by the transport roller pair 74. Further, the transported recording medium S is transported by a discharge roller pair 76. The discharge roller pair 76 is a pair of reversing rollers capable of rotating the rotation direction forward and backward, and at a timing when the rear end of the recording medium S is sandwiched. Has the function to reverse the direction of rotation.

  The recording medium S reversely conveyed by the reversely ejected discharge roller pair 76 is conveyed by the reverse switching member 107 to the conveyance path 133 constituting the second conveyance path. The recording medium S is sequentially conveyed by a conveyance roller pair 84, a registration roller pair 83, and a conveyance roller pair 82, and is conveyed along a conveyance path 132 that constitutes a second conveyance path. Next, the recording medium S transported by the transport roller pair 82 is guided to the transport path 111 constituting the second transport path by the switching member 108 and reaches the registration roller pair 73 in the first transport path again. Since the subsequent image forming process has been described above, it will be omitted.

  The recording medium S on which the toner images are fused and fixed on both sides passes through the conveyance path 122 and is conveyed by the conveyance roller pair 74. Further, the conveyed recording medium S is stacked on the discharge tray 65 by the discharge roller pair 76.

<Image creation process of single-sided image by inkjet method>
Next, the image forming unit 100 using the inkjet method will be described with reference to FIG.

  The recording medium S guided toward the second image forming unit 100 by the switching member 105 passes through the conveyance path 131 that guides the recording medium to the second conveyance path, and is conveyed by the conveyance roller pair 82 to the second. It is sent to a conveyance path 132 that constitutes a conveyance path. Then, the recording medium S sent to the transport path 132 is transported to the registration roller pair 83.

  The transport roller pair 82 rotates forward in the electrophotographic double-sided image forming process described above to transport the recording medium S in the downward direction as shown in the figure, but the rotation direction is switched between forward and reverse. Is possible. Therefore, the conveyance roller pair 82 can reversely convey the recording medium S in the upward direction as shown in the drawing when an image is formed by an image forming process using an inkjet method.

  Next, the registration roller pair 83 has a function of correcting the skew by following the leading end of the recording medium S by creating a loop by abutting the recording medium S conveyed from the conveyance roller pair 82. Further, it has a function of transporting the recording medium S to the ink jet type image forming unit 100 in accordance with the timing of image formation on the recording medium S, that is, the ink ejection timing of the ink jet type image forming unit.

  It goes without saying that the registration roller pair 83 can be switched between forward and reverse rotation when performing image formation by the ink jet method as described above.

  In the recording medium S, an image is formed by ejecting ink according to image information by the image forming unit 100 using an ink jet method. The recording unit of the image forming unit 100 includes, for example, yellow (Y), magenta (M), cyan (C), and black (K) recording heads 101Y, 102M, 103C, and 104K.

  As shown in FIG. 1, each of the recording heads 101Y, 102M, 103C, and 104K is an ink jet type line head having a nozzle row corresponding to a length (width) in a direction orthogonal to the conveyance direction of the recording medium.

  Yellow (Y), magenta (M), cyan (C), and black (K) inks are selectively ejected from these four recording heads 101Y, 102M, 103C, and 104K, respectively. Record an image.

  The ejected ink is supplied from an ink cartridge (not shown) to the corresponding recording heads 101Y, 102M, 103C, and 104K by a pump and a tube (not shown). Of course, the number of colors is not limited to four, and the color arrangement order is not limited to this.

  The recording medium S to which ink has been ejected by the ink jet method is conveyed to a conveyance path 133 that constitutes a second conveyance path by the reversed conveyance roller pair 84. The conveyed recording medium S is stacked on the discharge tray 65 by the discharge roller pair 76.

  As described above, in the present embodiment, when only the image by the ink jet method is formed, the second image forming unit 100 does not pass the recording medium through the first image forming unit 99 of the electrophotographic method. It is sent to the transport paths 133, 132, and 111 that are positioned. Therefore, when only the image by the ink jet method is formed, the recording medium is deteriorated due to the recording medium passing through the first image forming unit 99 of the electrophotographic method, and the first image forming unit 99 of the electrophotographic method is used. Deterioration can be prevented.

  Further, the second image forming unit 100 includes a first conveyance path (conveyance path 122) and a second conveyance path (conveyance paths 133 and 132) for guiding the recording medium to the first conveyance path again. It is possible to move between. Therefore, the apparatus can be reduced in size as compared with the configuration in which the image forming units 99 and 100 are connected in series.

  Further, from the viewpoint of energy saving, the image forming unit 99 using the electrophotographic method does not operate (for example, the fixing device 5 is not heated) while the image forming unit 100 using the ink jet method is performing image formation. Control of this operation is performed by a controller (CPU) 90 as a control unit described later.

<Image creation process of double-sided images by inkjet method>
Next, an image forming process of a double-sided image by the ink jet method will be described with reference to FIGS.

  As shown in FIG. 4, when printing the first surface, the ink jet image forming unit 100 is driven from a drive source (not shown) constituting a moving mechanism around a rotation shaft 201 of an ink jet head support frame 200 described later. The drive is transmitted to rotate. That is, the inkjet image forming unit 100 rotates 180 degrees in the direction of arrow B from the second recording position (dotted line position in FIG. 4), which is the initial position facing the transport path 132, and faces the transport path 122. Move to the first recording position.

  Then, the recording medium S passes through the conveyance paths 70 and 121, passes through the registration roller pair 73, the secondary transfer inner roller 32 and the secondary transfer outer roller 41, and the fixing device 5, and is conveyed by the conveyance roller pair 301. It is conveyed to. Here, the registration roller pair 73 functions as a simple conveying roller pair that creates a loop by abutting the recording medium S when an image is formed by an electrophotographic method, but does not create a loop when an image is formed by an inkjet method. To do. Further, the fixing device 5 in the first image forming unit 99 transports the recording medium S downstream as a transport path without heating.

  Next, the conveyance roller pair 301 functions as a registration roller pair for the first surface in an image forming process of a double-sided image by an inkjet method. In other words, the conveyance roller pair 301 has a function of correcting the skew by causing the recording medium S conveyed from the fixing device 5 to abut and creating a loop so as to follow the leading edge of the recording medium S. Further, it has a function of transporting the recording medium S to the ink jet type image forming unit 100 in accordance with the timing of image formation on the recording medium S, that is, the ink ejection timing of the ink jet type image forming unit.

  The recording medium S is transported by a pair of transport rollers 74 after an ink is ejected according to image information by the image forming unit 100 using an inkjet method to form an image. The transported recording medium S is transported by the discharge roller pair 76. The discharge roller pair 76 can reverse the rotation direction forward and backward, and reverses the rotation direction at the timing when the rear end of the recording medium S is sandwiched. Has function.

  Next, as shown in FIG. 5, when printing on the second side, the inkjet image forming unit 100 is driven by a drive source (not shown) that forms a moving mechanism around a rotation shaft 201 of an inkjet head support frame 200 described later. ) Is transmitted to rotate. That is, the inkjet image forming unit 100 rotates 180 degrees in the direction of arrow C from the first recording position (dotted line position in FIG. 5) that is the recording position of the first surface, and is the initial position facing the conveyance path 132. To the first recording position. At the same time, the recording medium S whose rear end is sandwiched between the discharge roller pair 76 passes through the transport path 133 by the reverse switching member 107 and is transported to the transport path 132 by the transport roller pair 84.

  Here, the conveyance roller pair 84 functions as a conveyance roller pair when an image is formed on one side and both sides of the recording medium by the electrophotographic method as described above, and when an image is formed on one side of the recording medium by the inkjet method. To do. However, when images are formed on both sides of a recording medium by the ink jet method, they function as a pair of registration rollers for the second surface in a double-sided image forming process by the ink jet method. That is, the conveyance roller pair 84 has a function of correcting the skew by causing the recording medium S reversely conveyed from the discharge roller pair 76 to abut and creating a loop so as to follow the leading edge of the recording medium S. . In addition, it has a function of transporting the recording medium S to the ink jet type image forming unit 100 in accordance with the timing of image formation on the recording medium S, that is, the ink ejection timing of the ink jet type image forming unit 100.

  The recording medium S is ejected in accordance with image information by the image forming unit 100 using an ink jet method to form an image, and then the recording medium S is sequentially transported in the transport path 132 by the registration roller pair 83 and the transport roller pair 82. Here, the registration roller pair 83 functions as a simple conveying roller pair that does not create a loop when an image is formed on both surfaces of a recording medium by an ink jet image forming unit.

  Next, the recording medium S transported by the transport roller pair 82 is guided to the transport path 111 by the switching member 108 and reaches the registration roller pair 73 in the first transport path again. The recording medium S on which images by the ink jet method are formed on both sides passes through the conveyance path 122 and is conveyed by the conveyance roller pair 74. The conveyed recording medium S is stacked on the discharge tray 65 by the discharge roller pair 76.

  In this embodiment, after ink is applied to both sides of the recording medium by the ink jet image forming unit 100, the recording medium is discharged to the discharge tray 65 by the discharge roller pair 76 through the conveyance path 111 and the conveyance path 122. Illustrated. However, after ink is applied to both sides of the recording medium by the ink jet image forming unit 100, the registration roller pair 83 and the conveyance roller pair 82 are rotated in the opposite directions, and the discharge roller pair 76 puts them on the discharge tray 65. You may comprise so that it may discharge | emit. Here, the reverse direction is a direction in which the recording medium S in the transport path 132 is transported upward.

  As described above, the image forming process of the double-sided image by the ink jet method has the same conveyance path of the recording medium S as the image forming process of the double-sided image by the electrophotographic method. In addition, the registration roller pair 73, the secondary transfer inner roller 32, the secondary transfer outer roller 41, and the fixing device 5 in the electrophotographic system function as a transport unit that transports the recording medium S. Further, the first-side transport roller pair 301 and the second-side transport roller pair 84 follow the leading edge of the recording medium S to correct skew, and in accordance with the ink discharge timing of the ink jet image forming unit. Functions as a pair of registration rollers that convey the image to the inkjet image forming unit 100. In addition, the image forming process of the double-sided image by the ink jet method is different from the image forming process of the single-sided image by the ink jet method in the first side. At the time of single-sided image formation, the registration roller pair 83 corrects the skew of the recording medium S and carries it to the ink jet type image forming unit 100 in accordance with the ink discharge timing of the ink jet type image forming unit. On the other hand, at the time of double-sided image formation (second side), the registration roller pair 83 functions as a conveying unit without performing skew correction of the recording medium S.

<Image creation process of double-sided image by combined use of electrophotographic method and inkjet method>
Next, an image forming process of a double-sided image by using both the electrophotographic method and the ink jet method will be described with reference to FIGS.

  The conveyance path of the recording medium S in this configuration is the same as the above-described double-sided image conveyance path by the electrophotographic method and the double-sided image conveyance path by the inkjet method.

  However, as an image forming process of the double-sided image by the ink jet method, the image forming unit 100 of the ink jet method rotates around the rotation shaft 201. That is, the inkjet image forming unit 100 faces the conveyance path 122 when printing the first side, and the inkjet image forming unit 100 faces the conveyance path 132 when printing the second side. On the other hand, in this configuration, in order to form images on both sides of the recording medium S, the inkjet image forming unit 100 is opposed to the conveyance path 132. That is, the inkjet image forming unit 100 is located at the second recording position, which is the initial position facing the conveyance path 132.

  The recording medium S stored in the recording medium storage 61 and 62 is transported through the transport paths 70, 121, and 122 until the rear end is nipped by the discharge roller pair 76. Meanwhile, the registration roller pair 73, the secondary transfer inner roller 32 and the secondary transfer outer roller 41, the transport roller pair 301, and the transport roller pair 74 operate as transport means only for transporting the recording medium S, and the fixing device 5 is It operates as a conveying means like the plurality of roller pairs without heating.

  Then, a double-sided image is formed on the recording medium S by the same image formation process as the second side of the double-sided image by the inkjet method and the same image formation process as the second side of the double-sided image by the electrophotographic method.

  That is, the recording medium S, the rear end of which is sandwiched by the discharge roller pair 76, passes through the transport path 133 by the reverse switching member 107, and the ink ejection timing of the inkjet image forming unit 100 by the transport roller pair 84 having a registration function. It is conveyed according to.

  The recording medium S is ejected in accordance with image information by the image forming unit 100 using an ink jet method to form an image, and then the recording medium S is sequentially transported in the transport path 132 by the registration roller pair 83 and the transport roller pair 82. Next, the recording medium S transported by the transport roller pair 82 is guided to the transport path 111 by the switching member 108 and reaches the registration roller pair 73 in the first transport path again. Then, an unfixed toner image is transferred to the recording medium S at the secondary transfer portion by an electrophotographic image forming process, and the toner image is melted and fixed by the fixing device 5. Thereafter, the recording medium S is transported by the transport roller pair 74 via the transport path 122 and stacked on the discharge tray 65 by the discharge roller pair 76.

  As described above, as an image forming process using both recording methods in this configuration, printing is first performed by the ink jet method, and then is printed by the electrophotographic method. Therefore, the user sets in advance whether to select the electrophotographic method or the ink jet method for the first and second surfaces of one recording medium, and according to the image forming process, the first surface is an ink jet method, and the second surface is an electrophotographic method. Or a double-sided image printed in advance on the second side by an inkjet method and printed on the first side by an electrophotographic method.

  As described above, when double-sided image printing is performed by using both the electrophotographic method and the ink jet method, the recording medium S is transported to the image forming unit 100 of the ink jet method so as not to be affected by the heat of the fixing device 5 as much as possible. The fixing device 5 is not heated. In addition, it is preferable that the ink jet image forming unit 100 is disposed not as a position directly above the fixing device 5 but as far as possible.

<Inkjet head rotation support configuration>
Next, a moving mechanism for rotatably supporting and moving the inkjet image forming unit 100 will be described with reference to FIGS. 6 and 7. FIG. 6 is a schematic top view illustrating the configuration of the ink jet image forming unit, and FIG. 7 is a cross-sectional operation explanatory diagram illustrating the operation of the ink jet image forming unit.

  First, a method of supporting the inkjet image forming unit 100 will be described with reference to FIG. In the inkjet image forming unit 100, protrusions 100a are integrally formed at both ends outside the maximum length (maximum width) in the width direction orthogonal to the conveyance direction of the recording medium S. The ink jet head support frame 200 includes an upper frame 202a, a lower frame 202b, and a side frame 202c. A compression spring 203 is disposed between the inkjet image forming unit 100 and the inkjet head support frame 200. In the above-described configuration, the position of the inkjet image forming unit 100 is regulated by the upper frame 202a and the lower frame 202b in the vertical direction, which is the conveyance direction of the recording medium, and the side frame 202c in the front-back direction, which is the width direction of the recording medium. . At the same time, the inkjet image forming unit 100 is movable with respect to the inkjet head support frame 200 by a compression spring 203. Here, the conveyance path 132 includes an inner guide 132a and an outer guide 132b, and the protrusion 100a abuts on the inner guide 132a. Accordingly, the distance between the inkjet image forming unit 100 and the recording medium S is appropriately maintained.

  Next, a method of rotating the inkjet image forming unit 100 will be described with reference to FIG. A rotation shaft 201 is provided on the side frame 202c. In the ink jet type image forming unit 100, the ink jet head support frame 200 can rotate 180 degrees around the rotation shaft 201. Therefore, the inkjet image forming unit 100 is configured to be movable to either the second recording position facing the transport path 132 or the first recording position facing the transport path 122.

  In FIG. 7A, as described above, the inkjet image forming unit 100 faces the conveyance path 132, and the protrusion 100a contacts the inner guide 132a. In this state, as described above, image formation on one side and both sides of the both sides by the ink jet method is performed.

  When the inkjet image forming unit 100 is rotated toward the conveyance path 122, as shown in FIG. 7B, the image forming unit 100 is moved in the direction of arrow a by a not-shown movement locking means, and the inner guide 132a is moved. The image forming unit 100 is retracted to a position sufficient to rotate. Thereafter, the image forming unit 100 of the ink jet system receives a drive from a drive source (not shown) around the rotation shaft 201 of the ink jet head support frame 200 and rotates 180 degrees in the direction of arrow B to the transport path 122. opposite.

  Thereafter, as shown in FIG. 7C, the movement locking means releases the locking of the ink jet type image forming unit 100 with respect to the ink jet head support frame 200 and moves the image forming unit 100 in the direction of arrow b. Here, similarly to the conveyance path 132, the conveyance path 122 includes an inner guide 122a and an outer guide 122b. However, as shown in FIG. The distance between the image forming unit 100 and the recording medium S is appropriately maintained. In this state, as described above, image formation is performed on the first side of the double-sided ink jet method by the ink-jet method and on the first side of both sides when the double-sided electrophotographic method and the ink-jet method are mixed.

  Then, when the inkjet image forming unit 100 is rotated toward the conveyance path 132, the image forming unit 100 is retracted to a position sufficient to rotate with respect to the outer guide 122b by a movement locking unit (not shown) as described above. To do. Then, the inkjet image forming unit 100 is rotated by 180 degrees in the direction of arrow C in FIG. 7D when a drive from a drive source (not shown) is transmitted around the rotation shaft 201 of the inkjet head support frame 200. Facing the transport path 132. Thereafter, the movement locking means releases the locking of the ink jet type image forming unit 100 with respect to the ink jet head support frame 200, and the protrusion 100a comes into contact with the inner guide 132a to return to the state shown in FIG. .

<Processes related to electrophotography and inkjet systems>
Here, the single-sided printing by each recording method, the double-sided printing with the same recording method, and the double-sided printing method in which the recording methods coexist will be described with respect to proper use of the electrophotographic method and the inkjet method.

  As shown in FIG. 9, the image forming apparatus is provided with a controller 90 as a control unit that controls the operation of the entire apparatus. The controller 90 determines whether the recording medium S stored in the recording medium storage 61, 62 is compatible with the image forming unit 99 using the electrophotographic method, the image forming unit 100 using the ink jet method, or according to the electrophotographic method. Whether the image forming unit 99 or the image forming unit 100 using the ink jet method is suitable is recorded in advance.

  For example, examples of paper types suitable for image formation by electrophotography include plain paper, thin paper of 64 g or less, and OHP. In addition, examples of paper types suitable for image formation by the inkjet method include inkjet-coated paper, embossed paper, envelopes, and the like, and paper sizes of A4, B5, LGL, and STMT, which are paper sizes of A4 or smaller, are listed. It is done.

  FIG. 8 is a flowchart showing image formation by selecting an image forming unit according to the recording medium S and image data, and FIG. 9 is a block diagram.

  The operation of the controller 90 when, for example, a print signal and image data are input from an external device to the image forming apparatus and information regarding the type of recording medium set by the user is input from an operation unit (not shown) is as follows. explain.

  Note that the information regarding the type of the recording medium may be input from a sensor that automatically determines the type of the recording material arranged in the recording medium storage 61, 62 or the like.

  If the print signal from the external device is a single-sided image (S11), a suitable image forming unit is selected from the electrophotographic image forming unit 99 and the inkjet image forming unit 100.

  If the compatible image forming unit is an electrophotographic system, image data is sent and image formation is performed by the electrophotographic image forming unit 99 (S13). If the suitable image forming unit is an inkjet system, image data is sent, the switching member 105 is operated (S15), and each pair of rollers in the second transport path starts to reverse (S16) and is positioned at the second recording position. An image is formed by the image forming unit 100 using the inkjet method (S17).

  Next, if it is determined in S11 that the image is not a single-sided image but a double-sided image, it is determined whether both sides of the image are to be formed by electrophotography (S18). If it is determined that both sides of the image are to be formed by the electrophotographic method, the first image is formed by the image forming unit 99 using the electrophotographic method (S19). Thereafter, the reverse switching member 107 is operated (S20), and image formation on the second surface is again performed by the image forming unit 99 using the electrophotographic method (S21).

  Next, if it is determined in S18 that no image is formed on both sides by the electrophotographic method, it is determined whether images are formed on both sides by the inkjet method (S22). If it is determined that both sides are to form an image by the ink jet method, the first image is formed by the ink jet type image forming unit 100 that has moved to the first recording position where the image is formed on the recording medium conveyed in the first conveyance path. (S23). Alternatively, image formation on the first surface is performed by the inkjet image forming unit 100 that has moved to the second recording position for forming an image on the recording medium transported in the second transport path (S23). Thereafter, the inkjet image forming unit 100 rotates and moves to a recording position opposite to the recording position of the first surface, thereby forming an image of the second surface. That is, the image is rotated to a position opposite to the opposite conveyance path when the image is formed on the first surface, and image formation on the second surface is performed by the inkjet image forming unit 100 (S24).

  Next, when it is determined in S22 that no image is formed by the inkjet method on both sides, it is determined that the image is formed on one side by the electrophotographic method and the other side is formed by the inkjet method (S25). Regardless of the first side and the second side, first, one-sided image formation is performed by the inkjet image forming unit 100 on the recording medium conveyed in the conveyance paths 133 and 132 of the second conveyance path (S26). . Thereafter, the other one-sided image is formed by the electrophotographic image forming unit 99 on the recording medium transported in the transport path 122 of the first transport path (S29).

  According to this embodiment, the inkjet image forming unit 100 is placed at the second recording position in the second transport path and the first recording position in the first transport path where the electrophotographic image forming unit 99 is located. It can move freely. Therefore, it is possible to select the recording position by the image forming unit 100 of the ink jet method in both cases where image formation is performed on one side of the recording medium or image formation is performed on both sides of the recording medium. For example, a recording position where the recording medium does not pass through the electrophotographic image forming unit 99 can be selected as a recording position by the ink jet image forming unit 100. As a result, recording can be performed by the inkjet image forming unit 100 at a position where the recording medium does not pass through the electrophotographic image forming unit 99. Therefore, when forming an image by the ink jet method, the recording medium deteriorates due to the recording medium passing through the first image forming unit 99 of the electrophotographic method, and the deterioration of the first image forming unit 99 of the electrophotographic method. Can be prevented.

  In addition, an ink jet capable of moving a recording position with respect to a first transport path for forming an image in the electrophotographic image forming unit 99 or a second transport path for guiding the recording medium to the first transport path again. By providing the image forming unit 100 of the system, it is possible to reduce the size of the apparatus.

[Second Embodiment]
Next, a second embodiment will be described based on FIGS. 10 to 12.

<Image formation process for double-sided image formation by inkjet method>
In the image forming process of double-sided image formation by the ink jet method in the first embodiment, the recording medium S is conveyed via the fixing device 5 without heating, but double-sided image formation is possible without going through the fixing device 5.

  FIG. 10 shows this configuration, and an intermediate switching member 302, an intermediate path 303, and an intermediate tray 304 are added to the first embodiment. The intermediate path 303 is provided to be branched from the first conveyance path between the first recording position by the second image forming unit 100 of the ink jet method and the first image forming unit 99 of the electrophotographic method. Transport path. The intermediate switching member 302 is provided so as to be switchable to the first transport path, and guides the recording medium on which the image is formed on the second image forming unit 100 of the ink jet method to the intermediate path 303 at the first recording position. This is a switching member. The intermediate tray 304 is a stacking member that temporarily stacks the recording medium guided to the intermediate path 303. The operation of the intermediate switching member 302 is controlled by the controller 90 described above.

  The image formation on the first side is the same as the image forming process of the single-sided image by the ink jet method in the first embodiment, but the rear end of the recording medium S is temporarily sandwiched by the discharge roller pair 76 in order to form the image on the second side. To do. As shown in FIG. 11, the inkjet image forming unit 100 rotates so as to face the conveyance path 122 of the first conveyance path, and the recording medium S is conveyed to the conveyance path 122 by the reverse switching member 107.

  Here, the conveyance roller pair 74 is a simple conveyance roller pair for conveying the recording medium S in the first embodiment, but has a registration roller function in the present embodiment. In other words, the front end of the recording medium S is abutted to create a loop so that the front end of the recording medium S is followed and skew correction is performed, and the recording medium S is conveyed in accordance with the ink ejection timing of the inkjet image forming unit 100. To do.

  The recording medium S on which the image formation on the second surface has been performed by the inkjet image forming unit 100 is conveyed by the conveyance roller pair 301, reaches the intermediate path 303 by the intermediate switching member 302, and is temporarily stacked on the intermediate tray 304. Is done. At this time, the rear end of the recording medium S is sandwiched between the conveyance roller pair 301.

  As shown in FIG. 12, the discharge roller pair 76, the transport roller pair 74, and the transport roller pair 301 rotate in the opposite direction to the image formation on the second surface, so that both surfaces are the ink jet image forming unit 100. The recording medium S on which an image is formed is stacked on a discharge tray.

  With the above configuration, double-sided image formation by the ink-jet image forming unit 100 is performed only in the transport path without operating the intermediate transfer belt 31 and the fixing device 5 which are main components of the electrophotographic image forming unit 99. The image forming process can be realized.

[Other Embodiments]
In the above-described embodiment, four image forming units (recording units) having different colors are used in both the electrophotographic method and the ink jet method, but the number and the order of arrangement are not limited and are necessary. What is necessary is just to set suitably according to.

  Further, in the above-described embodiment, the configuration in which the controller selects the image forming unit to be used according to the type and size of the recording medium is exemplified, but the present invention is not limited to this. For example, the image forming unit to be used may be appropriately selected by the user based on information from an operation unit (not shown) or an external device (not shown) such as a personal computer. Further, the type (paper type) and size of the recording medium are not limited to those exemplified in the above-described embodiment.

  In the above-described embodiment, the printer is exemplified as the image forming apparatus, but the present invention is not limited to this. For example, the image forming apparatus may be another image forming apparatus such as a copying machine or a facsimile machine, or another image forming apparatus such as a multi-function machine combining these functions. Further, the present invention is limited to an image forming apparatus that uses an intermediate transfer member, sequentially transfers toner images of respective colors onto the intermediate transfer member, and transfers the toner images carried on the intermediate transfer member collectively onto a recording medium. It is not something. For example, an image forming apparatus that uses a recording medium carrier and sequentially superimposes and transfers the toner images of the respective colors onto the recording medium carried on the recording medium carrier. The same effect can be obtained by applying the present invention to these image forming apparatuses.

S: Recording medium 5: Fixing device 11: Photoconductor 31 ... Intermediate transfer belt 32 ... Secondary transfer inner roller 41 ... Secondary transfer outer roller 73 ... Registration roller pair 74 ... Conveying roller pair 76 ... Discharge roller pair 82, 84 ... Conveying roller pair 83 ... Registration roller pair 90 ... Controller 99 ... First image forming unit 100 ... Second image forming units 101Y, 102M, 103C, 104K ... Recording heads 105, 108 ... Switching members 106, 111, 121, 122 , 131, 132, 133 ... transport path 107 ... reverse switching member 301 ... transport roller pair 302 ... intermediate switching member 303 ... intermediate path 304 ... intermediate tray

Claims (6)

A first transport path for guiding the recording medium;
A first image forming unit for forming an image by electrophotography on a recording medium conveyed through the first conveyance path;
A second transport path for reversing the front and back surfaces of the recording medium that has passed through the first transport path and guiding it to the first transport path;
A second image forming unit that forms an image by an ink jet method on a recording medium transported along the second transport path;
The second image forming unit forms an image on a recording medium conveyed along the first conveyance path from a second recording position where an image is formed on the recording medium conveyed along the second conveyance path. An image forming apparatus comprising: a moving mechanism that moves the first recording position. A control unit that controls the operation of the first image forming unit, the second image forming unit, and the moving mechanism;
The control unit moves the second image forming unit to the first recording position or the second recording position when the second image forming unit forms images on both sides of the recording medium. An image is formed on the first surface of the recording medium, and the image is formed on the second surface of the recording medium by moving to the first recording position or the second recording position different from the recording position on the first surface. The image forming apparatus according to claim 1.   The control unit is configured to form an image on one side of the recording medium by the first image forming unit, form an image on both sides of the recording medium by the first image forming unit, and form the second image. The image forming is performed on the recording medium by moving the second image forming unit to the second recording position when an image is formed on one side of the recording medium by the unit. Image forming apparatus.   When the second image forming unit forms an image on the recording medium, the control unit operates only as a conveying unit that conveys the recording medium without heating the fixing device in the first image forming unit. The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus.   A switching member for guiding the recording medium sent from the feeding means to the first transport path or the second transport path is provided, and the operation of the switching member is controlled by the control unit. The image forming apparatus according to any one of claims 2 to 4. An intermediate path branched from the first transport path between the first recording position by the second image forming unit and the first image forming unit, and the second recording unit at the first recording position. An intermediate switching member for guiding the recording medium on which the image is formed in the image forming unit to the intermediate path,
An image is formed by a second image forming unit located at the first recording position, and a recording medium heading for the first image forming unit is guided to the intermediate path by the intermediate switching member. Item 5. An image forming apparatus.

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