JP2010026298A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form images on both sides of a paper sheet by a one-time conveyance of the paper sheet, without making a structure more complex than needed. <P>SOLUTION: The image forming apparatus 1 comprises an electrophotographic module including: an image developing section 10 that develops toner image to be printed on paper sheet 9; a first transfer roller 11 that is disposed opposite the image developing section 10, having between them a paper conveyance path for conveying paper sheet 9, and applies a transfer voltage to transfer the toner image to the first main side 9a of the paper sheet 9; a transfer conveyance belt 12 that passes between the image developing section 10 and the first transfer roller 11 and circulates, while bearing the toner image transferred from the image developing section 10; a second transfer roller 13 that applies a transfer voltage to transfer the toner image, borne by the transfer conveyance belt 12, to the second main side 9b of the paper sheet 9. The image forming apparatus is configured, by connecting an image forming unit 2 including the electrophotographic module, a paper feed unit 3, and a fixing unit 4 so that they are freely detached. The number of the image forming units 2 can be changed according to the purpose. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image using an electrophotographic system.

  2. Description of the Related Art Conventionally, an image forming apparatus that forms an image using an electrophotographic method has an image forming unit that performs exposure, development, transfer, and fixing. Specifically, an electrostatic latent image is formed by exposing a print image on a photosensitive drum. It is generally known that after an image is formed, a toner image is attached (development), the toner image is transferred from the photosensitive drum to the paper, and the toner image transferred to the paper is fixed by heat and pressure. ing.

  In recent years, such an image forming apparatus has been widely used in offices and the like, and an image forming apparatus capable of forming an image on both sides of a sheet is demanded from the viewpoint of saving resources. In addition, the image transfer unit, fixing unit, paper feed unit, etc. are unitized to improve assembly during manufacturing and ease of replacement of parts during repair and replacement. There is a need for an image forming apparatus that can be arbitrarily increased and configured to have various specifications such as low-speed monochrome, high-speed monochrome, and color.

  Here, in the case of an image forming apparatus that realizes double-sided printing with one image forming unit, a method of forming an image on both sides by switching back a sheet is generally known. This method requires a position detection device that performs positioning and the like, and the control configuration becomes complicated. Further, since the paper must be stopped once when positioning is performed, the image forming speed is reduced.

  Therefore, a plurality of color image forming apparatuses each having a transfer paper supply unit and a storage unit after printing are arranged in series, and a reversing device for reversing the surface of the transfer paper is provided between them, without performing switchback. There has been a proposal that an image can be formed. (For example, refer to Patent Document 1.)

  In addition, a first image forming unit and a fixing device, and a second image forming unit and a fixing device, whose printing surfaces are opposite to each other, are provided and fed from two separately provided cassettes, respectively, and single-sided printing In this case, the recording paper output from the first image forming unit is bypassed, and in the case of duplex printing, the recording paper output from the first image forming unit is input to the second image forming unit. An image forming apparatus has been proposed. (For example, see Patent Document 2.)

  In addition, two image forming units having the same configuration are stacked in the upper direction of the plurality of cassettes, and each of the plurality of transfer papers is provided by a plurality of conveyance switching units provided around the lower image forming unit. The image forming apparatus performs one-sided recording in which each image forming unit is recorded in parallel and double-sided recording in which a transfer sheet recorded on one side by the lower image forming unit is reversed by a switchback and fed to the upper image forming unit. Proposals have been made. (For example, refer to Patent Document 3.)

On the other hand, the image transfer unit, the fixing unit, the paper feeding unit, etc. are unitized to improve the assemblability at the time of manufacture and the ease of replacement of parts at the time of repair and replacement. There has been no proposal of an image forming apparatus that can be arbitrarily increased to form various specifications such as low-speed monochrome, high-speed monochrome, and color.
JP-A-8-248695 JP 2000-284644 A JP 2007-163809 A

  However, in the technique of Patent Document 1, when the image is formed on both sides, the internal configuration of the reversing device is unknown, and it is not clear how the reversing device affects the image forming speed when the paper is reversed using the reversing device. There are technical challenges.

  In the technique of Patent Document 2, when an image is formed on one side, a sheet formed by the first image forming unit and a sheet formed by the second image forming unit are discharged to the front and back sides. There is a technical problem that complicated work such as rearrangement for reversing is required.

  In the technique of Patent Document 3, when forming images on both sides, paper is switched back to form an image. At this time, as described above, a position detection device that performs positioning and the like is necessary, and control is performed. There is a technical problem that the configuration becomes complicated. In addition, there is a technical problem that the image forming speed is reduced because the sheet must be stopped once when positioning is performed.

  Further, although the techniques of Patent Documents 1 to 3 can increase the image forming speed for forming images on both sides, a fixing device is provided in each of the two image forming units. There is a technical problem that power consumption is required.

  An object of the present invention is to provide an image forming technique capable of forming an image on both sides by a single conveyance of a sheet without complicating the structure more than necessary.

  Another object of the present invention is to provide a technique of an image forming apparatus capable of easily constructing various image forming apparatuses having different specifications such as monochrome and color image formation and increase / decrease in processing capacity. .

  An image forming apparatus of the present invention is provided to face an image developing unit that develops a toner image to be printed on a sheet, with the conveyance path for conveying the sheet interposed between the image developing unit and the toner image on the sheet. A first transfer roller that applies a transfer voltage to the first main surface and transfers the toner image that passes between the image developing unit and the first transfer roller and is transferred from the image developing unit; An electrophotographic apparatus comprising: a transfer conveyance belt that is carried and circulated; and a second transfer roller that transfers the toner image carried on the transfer conveyance belt by applying a transfer voltage to a second main surface of the paper. A module is provided.

  Further, the image forming apparatus is, for example, supported by the transfer conveyance belt with the transfer voltage of the first transfer roller that transfers the toner image from the image developing unit to the first main surface of the sheet. This is realized by high transfer voltage of the second transfer roller for transferring the toner image to the second main surface of the paper.

  Further, the image forming apparatus includes, for example, the electrophotographic module, first and second paper feeding ports for feeding the paper to the electrophotographic module, and one end connected to the first paper feeding port. A first paper feed path for supplying the paper to the first transfer roller and a second paper feed having one end connected to the second paper feed port and supplying the paper to the second transfer roller A path, a sheet conveyance path for carrying out the sheet by sandwiching both ends of the unfixed sheet on which the toner image has been transferred through the first and second transfer rollers, and the sheet conveyance path And an image forming unit including a first paper discharge port for discharging the paper.

  Further, in the image forming apparatus, for example, the sheet conveyance path includes a rolling support portion that makes point contact with a transfer area where the toner image is transferred onto the sheet.

  Further, the image forming apparatus includes, for example, two paper feed rollers that are detachably connected to the image forming unit and feed the paper to the first and second paper feed ports of the image forming unit. A sheet feeding unit including a sheet feeding cassette provided, and the unfixed sheet on which the toner image coming from the first sheet discharge port of the image forming unit is detachably connected to the image forming unit. And a fixing unit including a fixing unit for fixing the toner image.

  Further, in the image forming apparatus, for example, the image forming unit discharges the sheet to the second sheet feeding port of the other image forming unit connected to the downstream side in the sheet conveying direction. And the other end is connected to the second paper outlet, and the second paper outlet and the second paper outlet are connected to each other. A first relay path for relaying, a third paper feed port for receiving the paper carried out from the first paper discharge port of the other image forming unit connected to the upstream side of the paper conveyance direction, One end is connected to the third sheet feeding port, the other end is connected to the sheet conveying path, and the third sheet feeding port and the first sheet discharging port are relayed via the sheet conveying path. The second relay path is provided in contact with the image forming unit disposed at the upstream end in the sheet conveyance direction. A sheet feeding unit, and the fixing unit provided in contact with the image forming units arranged in the conveying direction downstream end of the paper, and includes.

  Further, in the image forming apparatus, for example, the image forming unit includes a plurality of the paper feeding cassettes that feed the paper independently of the first and second paper feeding ports. .

  Further, the image forming apparatus includes, for example, a third paper discharge port provided on the extension of the paper conveyance direction between the image developing unit and the first transfer roller, and is provided in the paper conveyance path. Is configured by providing a variable conveyance path movable in a horizontal posture for guiding the sheet to the third sheet discharge port.

According to the present invention, images can be formed on both sides by a single conveyance of a sheet without complicating the structure more than necessary.
In addition, it is possible to easily construct various image forming apparatuses having different specifications such as monochrome and color image formation and increase / decrease in processing capacity.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Embodiment 1)
FIG. 1 is a side sectional view schematically showing an internal configuration of an image forming apparatus according to the present embodiment. FIGS. 2A, 2B, 2C, and 2D are electrophotographic images constituting the image forming apparatus according to the present embodiment. FIG. 3 is a schematic diagram schematically showing each step of the operation of the module in order, FIG. 3 is an enlarged schematic diagram showing an enlarged view of the second transfer roller, and FIGS. 4A and 4B show the first transfer roller. FIG. 5A is an enlarged schematic diagram showing an enlarged view, FIG. 5A is a perspective view showing a paper transport mechanism, and FIG. 5B is a perspective view showing a state in which paper is fed into the paper transport mechanism.

  As shown in FIG. 1, the image forming apparatus 1 is a monochrome printer that prints on paper, and includes a resource-saving double-sided printing mechanism. The image forming apparatus 1 includes an image forming unit 2, a paper feeding unit 3, and a fixing unit 4. These are configured to be detachable from each other, and the number of image forming units 2 can be increased or decreased according to the purpose as will be described later.

  The image forming unit 2 according to the present embodiment is provided so as to face the image developing unit 10 that develops a toner image to be printed on the paper 9 and the image developing unit 10 across the conveyance path for conveying the paper 9. Is transferred between the first transfer roller 11 that applies a transfer voltage to the first main surface 9 a of the paper 9 and between the image developing unit 10 and the first transfer roller 11, and is transferred from the image developing unit 10. A transfer conveyance belt 12 that carries the toner image carried and circulates, and a second transfer that transfers the toner image carried on the transfer conveyance belt 12 by applying a transfer voltage to the second main surface 9b of the paper 9. An electrophotographic module including the roller 13 is provided.

  The image developing unit 10 includes a photosensitive drum 15 positioned on the upper surface of the conveyance path for conveying the paper 9, and surrounds the circumferential surface of the photosensitive drum 15, and includes a cleaner 16, a charging roller 17, an optical writing head 18, and a developing unit. A roller 19 is arranged. A first transfer roller 11 is disposed so as to face the photosensitive drum 15 with the transfer conveyance belt 12 interposed therebetween.

  The transfer conveying belt 12 is positioned below the image developing unit 10 and is sandwiched between the photosensitive drum 15 and the first transfer roller 11 so as to circulate in a counterclockwise direction indicated by an arrow a in FIG. It is formed in a loop shape.

  That is, the transfer conveyance belt 12 includes a first transfer roller 11, a first conveyance drum 20 disposed at the same height with respect to the first transfer roller 11, and a lower right side of the first transfer roller 11. Is held by the second transport drum 21 disposed in the position.

  A second transfer roller 13 is provided on the transfer conveyance belt 12 so as to face the second conveyance drum 21 on the downstream side in the rotation direction on the outer periphery and sandwich the transfer conveyance belt 12. .

  Then, on the right side of the image forming unit 2 including the electrophotographic module configured as described above, a first paper feeding port 22 for feeding paper 9 to the image forming unit 2 and a second paper feeding port. 23 and a third paper feed port 24 are arranged.

  The first paper feed port 22 is disposed at the same height with respect to the extension in the transport direction of the paper 9 between the image developing unit 10 and the first transfer roller 11. The second paper feed port 23 is disposed below the first paper feed port 22. The third paper feed port 24 is disposed above the first paper feed port 22.

  On the other hand, on the left side of the image forming unit 2, a first paper discharge port 25, a second paper discharge port 26, and a third paper discharge port 27 that are discharged from the image forming unit 2 are arranged. . The first paper discharge port 25 is arranged at the same height with respect to a fixing device 45 (fixing unit) of the fixing unit 4 described later. The second paper discharge port 26 is disposed at the same height as the second paper supply port 23. The third paper discharge port 27 is disposed at the same height as the first paper supply port 22. That is, the third paper discharge port 27 is arranged at the same height with respect to the extension of the sheet 9 in the transport direction between the image developing unit 10 and the first transfer roller 11.

  In addition, the image forming unit 2 of the present embodiment is connected to the first paper feed port 22 at one end, and the first paper feed port 22 supplies the paper 9 from the first paper feed port 22 to the first transfer roller 11. One end of the sheet feeding path 28 is connected to the second sheet feeding port 23, and the second sheet feeding path 29 supplies the sheet 9 from the second sheet feeding port 23 to the second transfer roller 13. It consists of

  Further, a paper transport path 30 is provided for transporting the paper 9 while sandwiching both ends of the unfixed paper on which the toner image is transferred through at least one of the first transfer roller 11 and the second transfer roller 13. It is configured to include.

  The paper transport path 30 is configured by stacking a plurality of transport belts. The first transport belt 31 is arranged in a flat loop shape in the vertical direction, and the first transport roller 32 is disposed on an extension line in the transport direction of the paper 9 between the image developing unit 10 and the first transfer roller 11. And a second conveying roller 33 disposed to face the first conveying roller 32.

  The second conveyor belt 34 is disposed at a position where the second conveyor belt 34 is bonded to the first conveyor belt 31 so as to face each other. The second conveyor belt 34 is disposed to be pressed below the first conveyor roller 32 of the first conveyor belt 31. The third transport roller 35 and a fourth transport roller 36 disposed opposite to the third transport roller 35 are arranged.

  The second transport belt 34 also functions as a variable transport path in which the fourth transport roller 36 is movably disposed and is movable in a horizontal posture for guiding the paper 9 to the third paper discharge port 27.

  The third conveyance belt 37 is located on the left side of the first conveyance belt 31 and is disposed at a position where the third conveyance belt 31 is bonded to the first conveyance belt 31 so as to face each other. A fifth transport roller 38 disposed, a sixth transport roller 39 disposed on the left side of the fifth transport roller 38, and a seventh transport roller disposed above the fourth transport roller 36. 40 and arranged. Further, since the first transport belt 31 and the third transport belt 37 have a long transport distance, auxiliary transport rollers are provided.

  The fourth conveyor belt 41 is located above the third conveyor belt 37, is disposed so as to face and contact the third conveyor belt 37, and is disposed above the second conveyor roller 33. It is arranged so as to be stretched over an eighth transport roller 42 and a ninth transport roller 43 disposed so as to face the upper direction of the sixth transport roller 39.

  Then, the sheet 9 that has passed between the first transfer roller 11 and the photosensitive drum 15 is between the first conveyance belt 31 and the second conveyance belt 34 in the sheet conveyance path 30, and between the first conveyance belt 31. And the third conveyor belt 37, between the third conveyor belt 37 and the fourth conveyor belt 41, reach the first paper discharge port 25, and are sent to the fixing unit 4.

  At this time, since the sheet 9 carries an unfixed toner image, in the present embodiment, the sheet 9 is configured using a sheet transport mechanism 100 as described below.

  That is, as shown in FIG. 5A, in the paper transport mechanism 100, the first transport belt 110 and the second transport belt 120 that transport the paper 9 while sandwiching both ends of the paper 9 are arranged in contact with each other. Yes. The first conveyor belt 110 is arranged so as to be stretched between the first conveyor roller 111 and the second conveyor roller 112. Further, the second conveyance belt 120 is arranged so as to be stretched between the third conveyance roller 121 and the fourth conveyance roller 122.

  At this time, as shown in FIG. 5B, the first conveyance belt 110 and the second conveyance belt 120 are arranged so as to convey the sheet 9 while sandwiching both end portions (non-transfer area 101) of the sheet 9. Yes. This prevents the toner image carried on the paper 9 from being damaged during conveyance.

  That is, the first transport belt 31 and the second transport belt 34 correspond to the first transport belt 110 and the second transport belt 120 shown in FIG. 5A. The first transport roller 32 and the second transport roller 33 correspond to the first transport roller 111 and the second transport roller 112 shown in FIG. The fourth transport roller 36 corresponds to the third transport roller 121 and the fourth transport roller 122.

  The first conveyor belt 31 and the third conveyor belt 37 correspond to the first conveyor belt 110 and the second conveyor belt 120 shown in FIG. 5A. The first transport roller 32 and the second transport roller 33 correspond to the first transport roller 111 and the second transport roller 112 shown in FIG. The fifth conveyance roller 38 corresponds to the third conveyance roller 121 and the fourth conveyance roller 122.

  The third conveyor belt 37 and the fourth conveyor belt 41 correspond to the first conveyor belt 110 and the second conveyor belt 120 shown in FIG. 5A. The fifth transport roller 38 and the sixth transport roller 39 correspond to the first transport roller 111 and the second transport roller 112 shown in FIG. The ninth conveyance roller 43 corresponds to the third conveyance roller 121 and the fourth conveyance roller 122.

  The image forming apparatus 1 including the image forming unit 2 formed in this way is arranged on the right side of the image forming unit 2, and the first paper feed port 22 and the second paper feed of the image forming unit 2. The sheet feeding unit 3 including a sheet feeding cassette 44 that feeds the sheet 9 to each of the ports 23 and the left side of the image forming unit 2 are discharged from the first sheet discharge port 25 of the image forming unit 2. And a fixing unit 4 including a fixing device 45 (fixing unit) for fixing the toner image on the sheet 9 on which the toner image is not fixed.

  Further, an image forming unit base 2a on which the image forming unit 2 is placed and a fixing unit base 4a on which the fixing unit 4 is placed are arranged below each unit.

  The paper feed unit 3 is provided with a paper feed cassette 44 below the inside, and this paper feed cassette 44 feeds the first paper 9 into the first paper feed port 22 and the second paper feed port 23 respectively. A sheet feeding roller 46 and a second sheet feeding roller 47 are provided. A controller unit 48 is disposed above the inside of the sheet feeding unit 3.

  The controller unit 48 includes a CPU (Central Processing Unit) (not shown), a ROM (Read Only Memory), an EEPROM (Rewritable Read Memory), a frame memory, an image data transfer circuit, etc., and is input from a host computer or the like. Print data is analyzed, print data is created and transferred to the image forming unit 2.

  In addition, the image forming unit 2 includes a CPU and a ROM (not shown). On the input side, data and command signals from the controller unit, a motor driver for driving a motor (not shown), and driving of the motor are transmitted to each unit. A predetermined bias current (bias) is supplied to the clutch driver for switching the driving system, the print driver for driving the optical writing head 18 based on the print data, the charging roller 17, the first transfer roller 11 and the second transfer roller 13. A bias power supply driver for supplying a voltage is connected.

  Next, the fixing unit will be described. In the fixing unit 4, a fixing device 45 for fixing the toner image transferred onto the paper 9 by the image forming unit 2 is disposed above the inside. The fixing device 45 is configured by arranging two fixing rollers having a heating function so as to be in pressure contact with each other in a direction orthogonal to the conveyance direction of the sheet 9.

  More specifically, the fixing device 45 rotates either the first fixing roller 49 or the second fixing roller 50 so that either the first fixing roller 49 or the second fixing roller 50 is in the opposite direction. And the fixing operation can be performed.

  Here, heaters (not shown) are respectively provided in the first fixing roller 49 and the second fixing roller 50 provided in the fixing device 45. In the present embodiment, all the rollers are provided with heaters. However, for example, only the first fixing roller 49 may be used as long as the fixing performance can be secured.

  Here, in the present embodiment, a configuration in which the paper feeding unit 3 and the fixing unit 4 are connected to both ends of one image forming unit 2 is not limited to this configuration, and a plurality of image forming units 2 are provided. Alternatively, the paper 9 may be connected in series in the conveyance direction, and the paper feed unit 3 and the fixing unit 4 may be connected to both ends thereof.

  That is, the image forming unit 2 has the following configuration for enabling connection with another image forming unit 2. Accordingly, each of the plurality of image forming units 2 includes a second paper discharge port 26 that discharges the paper 9 to the second paper supply port 23 of the image forming unit 2 disposed on the downstream side in the conveyance direction of the paper 9. One end is connected to the second paper supply port 23 and the other end is connected to the second paper output port 26, and the second paper supply port 23 and the second paper output port 26 are relayed. The first relay path 51, the third paper feed port 24 for receiving the paper 9 carried out from the first paper discharge port 25 of the image forming unit 2 arranged on the upstream side in the transport direction of the paper 9, and one end thereof The second paper feed port 24 is connected to the other end, the other end is connected to the paper transport path 30, and the second paper feed port 24 and the first paper discharge port 25 are relayed via the paper transport path 30. The relay route 52 is provided.

  Further, a third paper discharge port 27 for discharging the paper 9 is provided to the first paper supply port 22 of the image forming unit 2 arranged on the downstream side in the conveyance direction of the paper 9, and the second conveyance belt is provided. 34 is inclined in a direction parallel to the sheet conveyance direction, and is connected to the third paper discharge port 27.

  The second relay path 52 is configured by stacking a plurality of transport belts. The first conveyor belt 53 is arranged in a flat loop shape on the left and right, and is arranged so as to be stretched between the first conveyor roller 54 and the second conveyor roller 55. The second conveyor belt 56 is also arranged in a flat loop shape on the left and right, and is arranged so as to be stretched between the third conveyor roller 57 and the fourth conveyor roller 58.

  In this case, the second relay path 52 also has a plurality of transport belts arranged in an overlapping manner in the same manner as the paper transport path 30 described above in order to enable transport of the paper 9 carrying the unfixed toner image. The paper transport mechanism 100 is configured such that the transport belts facing each other among the plurality of transport belts are in contact with each other.

  That is, the paper transport mechanism 100 as shown in FIG. 5A is also arranged in the second relay path 52. Accordingly, as shown in FIG. 5B, when the paper 9 is transported, the paper 9 is transported with both end portions (non-transfer areas 101) being sandwiched. The correspondence relationship with the paper transport mechanism 100 shown in FIG. 5A is the same as that of the transport belts and transport rollers of the paper transport path 30 described above, and a description thereof will be omitted here.

Next, a printing process in the electrophotographic module of the image forming apparatus 1 of the present embodiment will be described with reference to FIGS. 2A to 2D.
2A to 2D are schematic diagrams sequentially showing each step of the operation of the electrophotographic module constituting the image forming apparatus according to the present embodiment. As a first step shown in FIG. 2A, an image to be printed on the second main surface 9 b of the paper 9 is developed on the photosensitive drum 15, and the image is transferred to the transfer conveyance belt 12 using the first transfer roller 11. Transfer to the outer peripheral surface.

  Note that the transfer conveyance belt 12 has a circumferential length of, for example, 430 mm or more. This perimeter is a length that can be used up to the case where the size of the sheet 9 is A3. That is, the transfer conveyance belt 12 holds an A3 size image in one rotation.

  Next, as a second step shown in FIG. 2B, a second step is performed via the second paper feed path 29 in accordance with the timing at which the leading edge of the image held on the transfer conveyance belt 12 reaches the second transfer roller 13. The sheet 9 is fed to the transfer roller 13. At this time, the second transfer roller 13 transfers the image held on the transfer conveyance belt 12 to the second main surface 9 b of the paper 9.

  As a third step shown in FIG. 2C, an image to be printed on the first main surface 9a of the paper 9 is formed on the photosensitive drum 15 in accordance with the timing when the paper 9 reaches the first transfer roller 11. Then, the sheet 9 is adhered to the transfer conveyance belt 12 and conveyed to the first transfer roller 11 to transfer the image.

  At this time, a voltage lower than that of the second transfer roller 13 is applied to the first transfer roller 11. With reference to FIGS. 3, 4A and 4B, as an example, when the voltage V1 applied to the second transfer roller 13 is 1400 V (see FIG. 3), the voltage is applied to the first transfer roller 11. When the voltage V2 is 1500 V, the image transferred by the second transfer roller 13 adheres to the transfer conveyance belt 12 (see FIG. 4A). Therefore, the first transfer roller 11 is set to a voltage lower than that of the second transfer roller 13, for example, V3 is set to 1000 V (see FIG. 4B).

  Next, as a fourth step shown in FIG. 2D, the sheet 9 on which images are transferred on both sides of the sheet 9 is conveyed to the sheet conveyance path 30. The sheet 9 on which the image is transferred is conveyed from the sheet conveyance path 30 to the fixing device 45.

  Here, the printing process when printing on both sides of the sheet 9 has been described. However, when printing on one side of the sheet 9, the sheet 9 is fed from the first sheet feed port 22 and the first process is performed. The paper passes through the paper feed path 28 and is conveyed to the first transfer roller 11.

  That is, in single-sided printing, the sheet 9 is fed between the first transfer roller 11 and the photosensitive drum 15 using the first paper feed path 28, and the toner image is directly transferred from the photosensitive drum 15.

  That is, when printing on one side of the paper 9, the transfer / conveying belt 12 and the second transfer roller 13 are not used. Accordingly, the sheet 9 on which the image has been transferred by the first transfer roller 11 is conveyed to the sheet conveyance path 30 and is conveyed from the sheet conveyance path 30 to the fixing device 45.

  As shown in FIG. 5B, the sheet conveyance path 30 conveys the sheet while holding both ends (non-transfer area 101) of the sheet. Further, the transfer area 102 is supported and conveyed by a plurality of rolling support portions 103. In this manner, the transfer region 102 is prevented from being disturbed by contacting members around the paper conveyance path 30.

  As described above, the image forming apparatus 1 according to the present embodiment can form an image by one transport without inverting the paper when forming images on both sides of the paper 9.

  Further, by making the image forming unit 2, the paper feeding unit 3, and the fixing unit 4 independent of each other, it is possible to configure image forming apparatuses having various specifications by combining arbitrary units.

(Embodiment 2)
FIG. 6 is a side sectional view schematically showing the internal configuration of the image forming apparatus according to the present embodiment. As shown in the figure, the image forming apparatus 60 of the present embodiment is also a monochrome printer that prints on paper as in the first embodiment, and includes a resource-saving duplex printing mechanism.

  The image forming apparatus 60 of the present embodiment includes a plurality of image forming units 2 (two in the present embodiment) arranged in series in the conveyance direction of the paper 9 and the paper 9 of the plurality of image forming units 2. The sheet feeding unit 3 is arranged on the upstream side in the conveyance direction, and the fixing unit 4 is arranged on the downstream side in the conveyance direction of the paper 9.

  In the present embodiment, the paper feed unit 3 is provided with a plurality of paper feed cassettes 44. The individual paper feed cassettes 44 are connected in common to the first paper feed port 22 and the second paper feed port 23, and the paper 9 is connected to both the first paper feed port 22 and the second paper feed port 23. Can be supplied. In addition, the first paper discharge port 25, the second paper discharge port 26, the third paper discharge port 27 of the upstream image forming unit 2, and the first paper supply port 22 of the downstream image forming unit 2. The second paper feed port 23 and the third paper feed port 24 are connected.

  Next, the printing process of the image forming apparatus according to the present embodiment will be described. The sheet 9 is fed from the second sheet feeding port 23 of the right image forming unit 2. At this time, paper is continuously fed to the second paper feed path 29 and the first relay path 51 of the right image forming unit 2. The sheet 9 sent to the first relay path 51 is fed to the second sheet feed path 29 of the left image forming unit 2.

  The sheet 9 fed to the second sheet feeding path 29 has images on both sides of the sheet 9 by the electrophotographic module of the right image forming unit 2 and the electrophotographic module of the left image forming unit 2. Transcribed.

  The sheets 9 on which the image is transferred by the electrophotographic module are respectively conveyed above the image forming unit 2 through the sheet conveying path 30. At this time, the sheet 9 on which the image has been transferred by the right image forming unit 2 is fed to the third sheet feed port 24 provided in the left image forming unit 2, and the left image forming unit 2 It passes through the second relay path 52 and is conveyed to the fixing device 45.

  As described above, the image forming apparatus 60 according to the present embodiment is configured to include one image forming unit 2 by including the right image forming unit 2 and the left image forming unit 2. Compared with the image forming apparatus 1, the image forming speed can be further increased.

  Further, by providing two paper feed cassettes 44 in the paper feed unit 3 as in the present embodiment, it is possible to feed paper continuously during paper feed, and paper is fed to one of the paper feed cassettes. Even if 9 disappears, an image can be formed without stopping the operation.

(Embodiment 3)
FIG. 7 is a side sectional view schematically showing the internal configuration of the image forming apparatus according to the present embodiment. As shown in the figure, an image forming apparatus 70 of the present embodiment is a tandem type color image forming apparatus.

  The image forming apparatus 70 according to the present embodiment includes a plurality of image forming units 2 (four in the present embodiment) arranged in series in the conveyance direction of the sheet 9 and the sheets 9 of the plurality of image forming units 2. The paper feed unit 3 is connected to the upstream side in the transport direction, and the fixing unit 4 is connected to the downstream side of the paper 9 in the transport direction.

  The plurality of image forming units 2 has a configuration in which four image forming units 2 (2Y, 2M, 2C, 2K) are arranged in a multistage manner from right to left in FIG. Of the four image forming units 2, three image forming units 2Y, 2M, and 2C on the upstream side in the conveyance direction of the sheet 9 are yellow (Y), magenta (M), and cyan (C), which are three primary colors of subtractive color mixing, respectively. ) Color image is formed, and the image forming unit 2K forms a monochrome image mainly with black (K) toner used for characters and dark portions of the image.

  In the case of the present embodiment, the second conveyance belt 34 is disposed so as to be inclined in a direction parallel to the conveyance direction of the paper 9. That is, as shown in the figure, the conveyance path of the sheet 9 is a linear conveyance path. In this way, the toner image of each color is transferred to the paper 9 by making the transport path of the paper 9 a linear transport path.

  Since the fixing unit 4 and the paper feeding unit 3 have the same configuration as that described in the first and second embodiments, description thereof is omitted here.

  Next, the printing process of this embodiment will be described. The sheet is fed from the first sheet feed port 22 of the image forming unit 2 on the upstream side in the conveyance direction of the sheet 9, passes through the first sheet feed path 28, and is transferred to the first sheet 9 by the first transfer roller 11. A yellow toner image is transferred to the main surface 9a.

  The sheet 9 on which the yellow toner image has been transferred passes through the second conveying belt 34 and the first sheet feeding of the image forming unit located on the downstream side in the conveying direction of the sheet 9 from the third sheet discharge port 27. Paper is fed to the mouth 22.

  Thus, the toner images of the respective colors are transferred in the order of yellow, magenta, cyan, and black.

  At this time, for a toner image of an unnecessary color, the sheet 9 only passes between the image developing unit 10 and the first transfer roller 11, and the toner image is not transferred. Also, for example, when only yellow and magenta toner images are required, the magenta toner image is transferred and then conveyed to the paper conveyance path 30 of the image forming unit 2 having the magenta toner image. The paper is discharged to the first paper discharge port 25.

  The paper 9 discharged from the first paper discharge port 25 is fed from the first paper discharge port 25 to the third paper feed port 24 of the image forming unit 2 located downstream in the transport direction of the paper 9. Is done. Then, it passes through the second relay path 52, is transported to the paper transport path 30, and is transported to the fixing device 45.

  In monochrome printing, the paper 9 fed from the paper feed cassette 44 is fed to the second paper feed port 23 of the image forming unit 2 having a yellow toner image, and the first paper The sheet 9 passes through the relay path 51 and is transported from the second sheet discharge port 26 to the second sheet feed port 23 of the image forming unit 2 disposed downstream in the sheet transport direction.

  Then, the sheet is passed through the second paper feed port 23, the first relay path 51, and the second paper discharge port 26 of the image forming unit 2 including the magenta toner image and the cyan toner image, and the black The sheet is fed to the second sheet feeding port 23 of the image forming unit 2 having the color toner image.

  In the case where the image forming units having the toner images of the respective colors are connected in this way, the misalignment position of the respective colors becomes a problem. That is, since there is a dimensional difference between the respective units, the image position of each color is shifted by simply connecting them.

  Therefore, a mode that changes the write timing of the write head and a test pattern for color matching are prepared, and the user can change the write timing while looking at the test pattern and easily adjust the overlay position of the core colors. The controller unit 48 is provided.

(Embodiment 4)
FIG. 8 is a side sectional view schematically showing the internal configuration of the image forming apparatus according to the present embodiment. As shown in the figure, the image forming apparatus is a monochrome printer that prints on paper, and includes a resource-saving duplex printing mechanism.

  The image forming apparatus 80 includes an electrophotographic module, an image forming unit 81 including a fixing unit disposed downstream in the transport direction of the electrophotographic module, and a right side of the image forming unit 81. It is composed of a paper feed unit 3.

  In this way, it is possible to provide an image forming apparatus that can be reduced in weight according to a user's request.

  According to the present embodiment, it is possible to produce double-sided printing by transporting the paper 9 once without any structure or process such as reversing the paper. In addition, by combining each unit into a unit and combining arbitrary units, various specifications such as monochrome, full color, and increase / decrease in printing capability according to customer needs can be easily configured.

1 is a side sectional view schematically showing an internal configuration of an image forming apparatus according to a first embodiment. FIG. 3 is a schematic diagram schematically showing a first step of the operation of the image forming apparatus. It is a schematic diagram schematically showing a second step of the operation of the image forming apparatus. FIG. 10 is a schematic diagram schematically showing a third step of the operation of the image forming apparatus. It is a schematic diagram which shows typically the 4th process of operation | movement of an image forming apparatus. It is the expansion schematic diagram which expanded and showed the 2nd transfer roller. It is the expansion schematic diagram which expanded and showed the 1st transfer roller. It is the expansion schematic diagram which expanded and showed the 1st transfer roller. FIG. 5 is an enlarged perspective view illustrating a paper conveyance path in an enlarged manner. FIG. 6 is an enlarged perspective view illustrating an enlarged state in which a sheet is passed through a sheet conveyance path. FIG. 5 is a side sectional view schematically showing an internal configuration of an image forming apparatus according to a second embodiment. FIG. 6 is a side cross-sectional view schematically illustrating an internal configuration of an image forming apparatus according to a third embodiment. FIG. 10 is a side cross-sectional view schematically showing an internal configuration of an image forming apparatus according to a fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image forming unit 2a Image forming unit base 2Y Image forming unit 2M Image forming unit 2C Image forming unit 2K Image forming unit 3 Paper feed unit 4 Fixing unit 4a Fixing unit base 9 Paper 9a First main surface 9b Second Main Surface 10 Image Developing Unit 11 First Transfer Roller 12 Transfer Conveying Belt 13 Second Transfer Roller 15 Photosensitive Drum 16 Cleaner 17 Charging Roller 18 Optical Writing Head 19 Developing Roller 20 First Conveying Drum 21 Second Transport drum 22 First paper feed port 23 Second paper feed port 24 Third paper feed port 25 First paper discharge port 26 Second paper discharge port 27 Third paper discharge port 28 First paper supply port Paper path 29 Second paper feed path 30 Paper transport path 31 First transport belt 32 First transport roller 33 Second transport roller 34 Second transport Feed belt 35 Third transport roller 36 Fourth transport roller 37 Third transport belt 38 Fifth transport roller 39 Sixth transport roller 40 Seventh transport roller 41 Fourth transport belt 42 Eight transport roller 43 9th transport roller 44 Paper feed cassette 45 Fixing device 46 1st paper feed roller 47 2nd paper feed roller 48 Controller part 49 1st fixing roller 50 2nd fixing roller 51 1st relay path 52 1st 2 relay route 53 1st conveyance belt 54 1st conveyance roller 55 2nd conveyance roller 56 2nd conveyance belt 57 3rd conveyance roller 58 4th conveyance roller 60 Image forming apparatus 70 Image forming apparatus 80 Image Forming apparatus 81 Image forming unit 81a Image forming unit base 100 Paper transport mechanism 101 Non-transfer area 102 Transfer area 103 Rolling Lifting unit 110 first conveyor belt 111 the first conveying roller 112 and the second conveying roller 120 and the second conveyor belt 121 the third conveying roller 122 fourth conveying rollers of

Claims (8)

An image developing unit for developing a toner image to be printed on paper;
A first transfer roller provided opposite to the image developing unit across a conveyance path for conveying the paper, and transferring the toner image to the first main surface of the paper by applying a transfer voltage;
A transfer conveying belt that passes between the image developing unit and the first transfer roller and carries the toner image transferred from the image developing unit and circulates;
An electrophotographic module comprising: a second transfer roller that transfers the toner image carried on the transfer conveyance belt by applying a transfer voltage to the second main surface of the paper;
An image forming apparatus comprising: The toner image carried on the transfer conveyance belt is transferred from the image developing unit to the second main surface of the sheet by the transfer voltage of the first transfer roller that transfers the toner image to the first main surface of the sheet. The transfer voltage of the second transfer roller to be transferred to the main surface is high;
The image forming apparatus according to claim 1. The electrophotographic module;
First and second paper feed ports for feeding the paper to the electrophotographic module;
A first paper feed path, one end of which is connected to the first paper feed port, and feeds the paper to the first transfer roller;
A second paper feed path having one end connected to the second paper feed port and supplying the paper to the second transfer roller;
A paper transport path for carrying out the paper while sandwiching both ends of the unfixed paper on which the toner image has been transferred through at least one of the first and second transfer rollers;
An image forming unit including a first paper discharge port connected to a downstream side of the paper conveyance path in the paper conveyance direction and for discharging the paper;
The image forming apparatus according to claim 1, further comprising: The paper transport path is a rolling support portion that makes point contact with a transfer area where the toner image is transferred to the paper,
The image forming apparatus according to claim 3, further comprising: A paper feed cassette that is detachably connected to the image forming unit and includes first and second paper feed rollers that feed the paper to the first and second paper feed ports of the image forming unit, respectively. Including a paper feed unit;
A fixing unit that is detachably connected to the image forming unit and includes a fixing unit that fixes the toner image onto the unfixed sheet on which the toner image coming from the first paper discharge port of the image forming unit is transferred. Unit,
The image forming apparatus according to claim 3, further comprising: The image forming unit includes: a second paper discharge port that discharges the paper to the second paper supply port of another image forming unit connected to the downstream side in the conveyance direction of the paper;
A first relay that has one end connected to the second paper feed port and the other end connected to the second paper discharge port, and relays between the second paper feed port and the second paper discharge port. Route,
A third paper feed port for receiving the paper carried out from the first paper discharge port of the other image forming unit connected to the upstream side of the paper conveyance direction;
One end is connected to the third sheet feeding port, the other end is connected to the sheet conveying path, and the third sheet feeding port and the first sheet discharging port are relayed via the sheet conveying path. A second relay route;
The paper feeding unit provided in contact with the image forming unit disposed at the upstream end of the paper conveyance direction;
The fixing unit provided in contact with the image forming unit disposed at the downstream end in the sheet conveyance direction;
The image forming apparatus according to claim 3, further comprising: The image forming unit includes a plurality of paper feed cassettes that feed the paper independently to each of the first and second paper feed ports.
The image forming apparatus according to claim 3, further comprising: A third paper discharge port is provided on the extension of the paper conveyance direction between the image developing unit and the first transfer roller, and the third paper discharge path is provided in the paper conveyance path. A variable transfer path is provided that is movable in a horizontal position that leads to the paper mouth.
The image forming apparatus according to claim 3.