Image forming apparatus

Abstract

To reduce the interval between a secondary transfer unit and a secondary transfer unit arranged side by side in a conveyance direction, compared with a case where an image forming unit is between an intermediate transfer body and an intermediate transfer body.SOLUTION: An image forming apparatus 10 comprises: a conveying belt 21 that conveys a recording sheet along a conveyance path; a first image forming group 31 that is composed of a plurality of image forming units 32; a second image forming group 51 that is provided on the downstream side in a conveyance direction of the first image forming group 31 and composed of a plurality of image forming units 52; a first intermediate transfer body 40 that is provided on the downstream side in the conveyance direction of the first image forming group 31 and to which toner images formed by the plurality of image forming units 32 are transferred; a second intermediate transfer body 60 that is provided on the upstream side in the conveyance direction of the second image forming group 51 and to which toner images formed by the plurality of image forming units 52 are transferred; a first transfer unit 74 that transfers the toner images to a recording sheet conveyed by the conveying belt 21 from the first intermediate transfer body 60; and a second transfer unit 76 that transfers the toner images to the recording sheet conveyed by the conveying belt 21 from the second intermediate transfer body 60.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an image forming apparatus.

Background Art

[0002] Patent Document 1 discloses a technique related to an image forming apparatus such as an electrophotographic copying machine and a printer, and particularly relates to an improvement in a duplex image forming apparatus capable of forming a duplex image. In this prior art, an air conveyance means disposed on at least one side of a recording material conveyance path between the most downstream transfer means and the fixing means, a recording material detection means for detecting information of the conveyed recording material, and an air flow rate control means for controlling the air flow rate of the air conveyance means based on the detection result from the recording material detection means are provided. Further, one or a plurality of rows of star wheels are rotatably provided on at least one side of the recording material conveyance path in the conveyance direction of the recording material. Further, an interim fixing means capable of interim fixing an unfixed image on at least one side of the recording material is provided, and the interim fixed recording material is guided to the fixing means by a recording material guiding member.

[0003] Patent Document 2 discloses a technique related to an image forming apparatus, particularly an image forming apparatus capable of forming a developer image based on image information. In this prior art, a color printer capable of forming a developer image based on image information includes a main body having a plurality of first image forming units, a first transfer belt, and an elastic roller. The first image forming unit is a unit capable of forming an image of each color based on image information. The first transfer belt is for transferring the images formed by the first image forming units respectively. The intermediate transfer roller has at least a surface formed of an elastic member, and transfers the image from the first transfer belt and transfers the transferred image to the paper. The main body can house the first image forming unit, the first transfer belt, and the intermediate transfer roller therein, and has a shutter portion disposed near the intermediate transfer roller and capable of being opened and closed.

[0004] Patent Document 3 discloses a color image duplication system in which a developed image is transferred from an image forming member to a receiving material via at least one intermediate transfer member. This prior art includes two toner image acquisition devices, toner, and first and second toner image acquisition devices each having toner. The first toner image acquisition device transfers the toner to the second toner image acquisition device, and the second toner image acquisition device transfers the toner to the receiving material. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-44973 [Patent Document 2] Japanese Patent Publication No. 2009-3236 [Patent Document 3] Japanese Patent Publication No. 2014-13388 [Overview of the project] [Problems that the invention aims to solve]

[0006] In an image forming apparatus that sequentially transfers toner images from multiple intermediate transfer bodies, each having a primary toner image transferred to it, onto a transported recording medium to superimpose the toner images, if the distance between secondary transfer units aligned in the transport direction is wide, the recording medium is more likely to move away from the transport path.

[0007] The object of the present invention is to narrow the space between secondary transfer sections aligned in the transport direction of the recording medium by the transport means, compared to the case where an image forming section is located between intermediate transfer sections in the transport direction of the recording medium by the transport means. [Means for solving the problem]

[0008] The first embodiment is an image forming apparatus comprising: a transport means for transporting a recording medium along a transport path in contact with one surface of the recording medium; a first image forming group provided on the other surface side of the recording medium along the transport path and comprising a plurality of image forming units that form a toner image; a second image forming group provided on the downstream side in the transport direction of the first image forming group on the other surface side of the recording medium along the transport path and comprising a plurality of image forming units that form a toner image; a first intermediate transfer body provided on the downstream side in the transport direction of the first image forming group and onto which the toner image formed by the plurality of image forming units of the first image forming group is primary transferred; a second intermediate transfer body provided on the upstream side in the transport direction of the second image forming group and onto which the toner image formed by the plurality of image forming units of the second image forming group is primary transferred; a first transfer unit that secondaryly transfers the toner image from the first intermediate transfer body to the other surface of the recording medium transported by the transport means; and a second transfer unit that secondaryly transfers the toner image from the second intermediate transfer body to the other surface of the recording medium transported by the transport means.

[0009] The second embodiment is an image forming apparatus according to the first embodiment, wherein the conveying means is a conveying belt wrapped around a tensioned roll and a drive roll, and the distance between the first transfer section and the second transfer section on the conveying belt is set to an integer multiple of the circumferential length of the drive roll.

[0010] In the third embodiment, the distance between the first transfer section and the second transfer section in the conveyor belt is the same as the circumferential length of the drive roll. difference This is an image forming apparatus according to the second embodiment, which is configured as follows.

[0011] The fourth embodiment is the image forming apparatus according to the first embodiment, wherein the distance between the first transfer unit and the second transfer unit is set to be less than or equal to the minimum width in the transport direction of the recording medium on which an image can be formed.

[0012] The fifth embodiment is the image forming apparatus according to the fourth embodiment, wherein the distance between the first transfer unit and the second transfer unit is set to be smaller than the minimum width in the transport direction of the recording medium for which an image can be formed.

[0013] The sixth embodiment is an image forming apparatus according to any one of the first to fifth embodiments, wherein the first intermediate transfer body is a first intermediate transfer belt stretched with its longitudinal direction intersecting the transport path in a side view from the direction of the rotation axis, and the plurality of image forming units constituting the first image forming group are arranged in the longitudinal direction on the upstream side of the first intermediate transfer belt in the transport direction.

[0014] The seventh embodiment is an image forming apparatus according to the sixth embodiment, further comprising a first cleaning member for cleaning the first intermediate transfer belt, wherein the first cleaning member is positioned to clean the longitudinal folded end of the first intermediate transfer belt after secondary transfer, or the space between the folded end and the first image forming group.

[0015] The eighth embodiment is an image forming apparatus according to any one of the first to seventh embodiments, wherein the second intermediate transfer body is a second intermediate transfer belt stretched with its longitudinal direction intersecting the transport path in a side view from the direction of the rotation axis, and the plurality of image forming units constituting the second image forming group are arranged in the longitudinal direction downstream of the second intermediate transfer belt in the transport direction.

[0016] The ninth aspect is an image forming apparatus according to the eighth aspect, further comprising a second cleaning member for cleaning the second intermediate transfer belt, wherein the second cleaning member is positioned to clean the space between the second transfer section and the second image forming group after secondary transfer of the second intermediate transfer belt.

[0017] The tenth embodiment is an image forming apparatus according to any one of the first to ninth embodiments, wherein an electrical substrate is arranged on the upstream side in the transport direction of the first image forming group or on the downstream side in the transport direction of the second image forming group. [Effects of the Invention]

[0018] According to the first aspect, the distance between the first transfer portion and the second transfer portion in the conveyance path can be narrowed as compared with the case where there is an image forming unit between the first intermediate transfer body and the second intermediate transfer body arranged in the conveyance direction that narrow the space between the secondary transfer portions arranged in the conveyance direction.

[0019] According to the second aspect, the influence of uneven rotation of the driving roll is small as compared with the case where the distance between the first transfer portion and the second transfer portion on the conveyance belt is not an integral multiple of the circumferential length of the driving roll.

[0020] According to the third aspect, the distance between the first transfer portion and the second transfer portion on the conveyance belt can be narrowed as compared with the case where the circumferential length of the driving roll is two times or more.

[0021] According to the fourth aspect, the separation of the smallest recording medium capable of image formation conveyed between the first transfer portion and the second transfer portion from the conveyance path is suppressed as compared with the case where the distance between the first transfer portion and the second transfer portion is larger than the width in the conveyance direction of the smallest recording medium capable of image formation.

[0022] According to the fifth aspect, the separation of the smallest recording medium capable of image formation conveyed between the first transfer portion and the second transfer portion from the conveyance path is suppressed as compared with the case where the distance between the first transfer portion and the second transfer portion is equal to or larger than the width in the conveyance direction of the smallest recording medium capable of image formation.

[0023] According to the sixth aspect, the distance between the first transfer portion and the second transfer portion in the conveyance path can be narrowed as compared with the case where the first intermediate transfer body is a drum.

[0024] According to the seventh aspect, the distance between the first transfer portion and the second transfer portion in the conveyance path can be narrowed as compared with the case where a first cleaning member is provided on the first intermediate transfer body and the second intermediate transfer body.

[0025] According to the eighth aspect, the distance between the first transfer portion and the second transfer portion in the conveyance path can be narrowed as compared with the case where the second intermediate transfer body is a drum.

[0026] According to the ninth embodiment, the distance between the first transfer section and the second transfer section in the transport path can be narrowed compared to the case where a second cleaning member is provided between the first intermediate transfer section and the second intermediate transfer section.

[0027] According to the tenth embodiment, the distance between the first transfer section and the second transfer section in the transport path can be narrowed compared to the case where there is an electrical substrate between the first intermediate transfer section and the second intermediate transfer section. [Brief explanation of the drawing]

[0028] [Figure 1] This is a configuration diagram of the image forming apparatus according to the first embodiment. [Figure 2] This is an enlarged view of the main part of Figure 1. [Figure 3] This is a schematic diagram of the main part of the image forming apparatus according to the first embodiment. [Figure 4] This is a schematic diagram of the main part of the image forming apparatus according to the first embodiment. [Figure 5] This is a schematic diagram of the main components of an image forming apparatus as an example. [Figure 6] Block diagram showing the configuration of control devices, etc. [Modes for carrying out the invention]

[0029] <First Embodiment> An image forming apparatus according to a first embodiment of the present invention will be described.

[0030] In Figure 1, the width direction of the image forming apparatus 10 is denoted as the X direction, the height direction as the Y direction, and the depth direction as the Z direction, indicated by the arrows X, Y, and Z, respectively. When it is necessary to distinguish between one side and the other in the X, Y, and Z directions, the right side of the image forming apparatus 10 in Figure 1 is described as the +X side, the left side as the -X side, the top side as the +Y side, the bottom side as the -Y side, the front side as the +Z side, and the rear side as the -Z side. Viewing from the depth direction (Z direction) is referred to as a side view.

[0031] In this embodiment, recording paper P is used as an example of a recording medium, and the upstream side in the transport direction in which the recording paper P is transported is referred to as the "transport direction upstream side," and the downstream side in the transport direction is referred to as the "transport direction downstream side." In this embodiment, the image forming apparatus 10 is a so-called single-pass system, and printing is performed by the recording paper P passing in front of the image forming unit 30 and the image forming unit 50, which will be described later, only once each.

[0032] [Overall structure] First, I will explain the overall configuration of the image forming apparatus.

[0033] As shown in Figure 1, the image forming apparatus 10 includes a storage unit 12 for storing recording paper P (see also Figure 3) as an example of a recording medium, a transport unit 11 for transporting the recording paper P along a transport path 19, and image forming units 30 and 50 for forming toner images to be transferred to the recording paper P. The "transport direction" is the direction in which the recording paper P is transported along the transport path 19.

[0034] The storage section 12 is retractable from the main body 10A of the image forming apparatus 10, and stores the recording paper P inside.

[0035] The transport unit 11 is equipped with, in order from the upstream side in the transport direction, a discharge roll 13, a transport roll 14, a pair of resist rolls 15, a transport belt device 20, a fixing device 18, and a discharge roll 17, etc.

[0036] The discharge roll 13 sends the recording paper P stored in the storage unit 12 to the transport path 19 that constitutes the transport unit 11. The transport roll 14 transports the recording paper P along the transport path 19.

[0037] The resist roll pair 15 transports the recording paper P, which has been transported by the transport roll 14, to the upstream secondary transfer position TJ2, which will be described later. The resist roll pair 15 sandwiches the recording paper P between the resist roll 15A and the pinch roll 15B and transports the recording paper P downstream in the transport direction.

[0038] The conveyor belt device 20 transfers the toner image formed by the image forming units 30 and 50 onto the recording paper P, while transporting the recording paper P downstream along the transport path 19. Details of the conveyor belt device 20 will be described later.

[0039] The fixing device 18 has a pair of fixing rolls 16, and heats and pressurizes the recording paper P on which the toner image has been transferred as it passes between the pair of fixing rolls 16, thereby fixing the toner image to the recording paper P.

[0040] The discharge roll 17 discharges the recording paper P, on which the toner image has been fixed by the fixing device 18, to the discharge unit 9.

[0041] The image forming unit 30 and the image forming unit 50 are arranged side by side in the vertical direction. In this embodiment, the image forming unit 50 is positioned above the image forming unit 30. From another perspective, the image forming unit 50 is positioned downstream of the image forming unit 30 in the transport direction.

[0042] As shown in Figures 2 and 3, the image forming unit 30 comprises a plurality of image forming units 32, four in this embodiment, and an endless first intermediate transfer belt 40. The four image forming units 32 are referred to as the first image forming group 31. The first intermediate transfer belt 40, as an example of the first intermediate transfer body, is mounted so as to be rotatable counterclockwise when viewed from the front in Figure 2, and onto which the toner image formed by the four image forming units 32 is transferred.

[0043] The image forming unit 32 comprises an image forming unit 32W that forms a white toner image, an image forming unit 32M that forms a magenta toner image, an image forming unit 32C that forms a cyan toner image, and an image forming unit 32Y that forms a yellow toner image. These four image forming units 32 are arranged in the order of image forming unit 32Y, image forming unit 32M, image forming unit 32C, and image forming unit 32W, starting from the upstream side (closer to the support roll 44, which will be described later) in the rotational direction of the first intermediate transfer belt 40. Note that Y, M, C, and W are omitted in the description when it is not necessary to distinguish between them.

[0044] Furthermore, in the following, the upstream side in the rotational direction of the first intermediate transfer belt 40 will be referred to as the "upstream side in the rotational direction," and the downstream side in the rotational direction will be referred to as the "downstream side in the rotational direction." In other words, in the image forming unit 32, the image forming unit 32W is located on the furthest downstream side in the rotational direction.

[0045] As shown in Figure 2, the image forming unit 32 includes a photoreceptor 33, a photoreceptor charging member 34 that charges the peripheral surface of the photoreceptor 33, an exposure device 35 that irradiates the charged photoreceptor 33 with exposure, and a developing device 36 that develops the electrostatic latent image formed by the exposure and visualizes it as a toner image.

[0046] The developing apparatus 36 has developing rolls 39Y, 39M, 39C, and 39W, and each has a developing bias applied by the power supply unit 99 (see Figure 5).

[0047] Furthermore, primary transfer rolls 37Y, 37M, 37C, and 37W are positioned opposite each photoreceptor 33 across the first intermediate transfer belt 40 to transfer the toner image formed by the image forming unit 32 to the first intermediate transfer belt 40. The first intermediate transfer belt 40 is wrapped around a support roll 44 that supports the first intermediate transfer belt 40 and a backup roll 42 that is positioned in the upstream first transfer unit 74, which will be described later. The primary transfer unit 70 is composed of the photoreceptor 33, the primary transfer rolls 37, and the first intermediate transfer belt 40. The positions between the photoreceptors 33Y, 33M, 33C, and 33W and the first intermediate transfer belt 40 are designated as primary transfer positions TY1, TM1, TC1, and TW1, respectively.

[0048] The image forming unit 50 has the same configuration as the aforementioned image forming unit 30, except that it forms images of different colors.

[0049] As shown in Figures 2 and 3, the image forming unit 50 comprises multiple image forming units 52, or four in this embodiment, and a second intermediate transfer belt 60. The four image forming units 52 are referred to as the second image forming group 51. The second intermediate transfer belt 60, as an example of a second intermediate transfer body, is mounted so as to be rotatable counterclockwise when viewed from the front in Figure 2, and onto which the toner image formed by the four image forming units 52 is transferred.

[0050] Furthermore, the image forming section 52 has the same configuration as the image forming section 32 of the image forming unit 30, except that the color being formed is different. Also, the second intermediate transfer belt 60 and the primary transfer roll 57, which will be described later, have the same configuration as the first intermediate transfer belt 40 and primary transfer roll 37 of the image forming unit 30. In addition, the other components constituting the image forming unit 50 are the same as those of the image forming unit 30.

[0051] As shown in Figure 2, the image forming unit 52 includes an image forming unit 52K that forms a black toner image, an image forming unit 52G that forms a gold toner image, an image forming unit 52S that forms a silver toner image, and an image forming unit 52T that forms a transparent toner image. Note that T, S, G, and K are omitted in the description when it is not necessary to distinguish between them.

[0052] The four image forming units 52 are arranged in the following order from the upstream side in the rotation direction (the side closer to the support roll 64, which will be described later): image forming unit 52T, image forming unit 52S, image forming unit 52G, and image forming unit 52K. In other words, in the image forming unit 52, image forming unit 52K is located furthest downstream in the rotation direction, image forming unit 52G and image forming unit 52S are located upstream of image forming unit 52K in the rotation direction, and image forming unit 52T is located furthest upstream in the rotation direction.

[0053] The image forming unit 52 includes a photoreceptor 53, a photoreceptor charging member 54, an exposure device 55, and a developing device 56.

[0054] The developing apparatus 56 has developing rolls 59T, 59S, 59G, and 59K, and each has a developing bias applied by the power supply unit 99 (see Figure 4).

[0055] Furthermore, primary transfer rolls 57T, 57S, 57G, and 57K are positioned opposite each photoreceptor 53 across the second intermediate transfer belt 60. The second intermediate transfer belt 60 is wound around a support roll 64 and a backup roll 62 located in the downstream second transfer section 76, which will be described later. The primary transfer section 72 is composed of the photoreceptors 53, primary transfer rolls 57, and the second intermediate transfer belt 60. The positions between the photoreceptors 53T, 53S, 53G, and 53K and the second intermediate transfer belt 60 are designated as primary transfer positions TT1, TS1, TG1, and TK1, respectively.

[0056] Furthermore, the developing devices 36 of each color image forming section 32 of the image forming unit 30 and the developing devices 56 of each color image forming section 52 of the image forming unit 50 are connected via supply lines to multiple toner cartridges (not shown) each containing toner corresponding to each color. The toner contained in each toner cartridge is supplied to the respective color developing devices 36 and 56 via the supply lines as needed when a supply device (not shown) provided in the supply lines is activated.

[0057] [Conveyor belt system] Next, we will describe the details of the conveyor belt device 20.

[0058] As shown in Figures 2 and 3, the conveyor belt device 20 includes an endless conveyor belt 21, a tensioning roll 22 that supports and tensions the conveyor belt 21, a drive roll 23 that rotates the conveyor belt 21, and secondary transfer rolls 24 and 25 positioned opposite the backup rolls 42 and 62, with the first intermediate transfer belt 40 and the second intermediate transfer belt 60 in between.

[0059] As an example of a conveying means, the conveyor belt 21 is stretched by tension rolls 22 and drive rolls 23, which are spaced apart in the direction of conveying the recording paper P (see Figure 3), and in this embodiment, in the vertical direction (Y direction). The drive rolls 23 rotate by a drive mechanism (not shown), causing the endless conveyor belt 21 to rotate. The tension rolls 22 rotate in conjunction with the rotation of the conveyor belt 21.

[0060] In this embodiment, the transport direction of the recording paper P transported by the transport belt device 20 is the Y direction.

[0061] The secondary transfer roll 24, with the recording paper P (see Figures 1 and 4) and the transport belt 21 sandwiched between it and the backup roll 42, transfers the toner image formed on the first intermediate transfer belt 40 of the image forming unit 30 to the surface PA (see Figure 3) of the recording paper P being transported by the transport belt 21. Similarly, the secondary transfer roll 25, with the recording paper P and the transport belt 21 sandwiched between it and the backup roll 62, transfers the toner image formed on the second intermediate transfer belt 60 of the image forming unit 50 to the surface PA (see Figure 3) of the recording paper P.

[0062] As shown in Figure 3, the side of the recording paper P on which the toner image is transferred is referred to as surface PA, and the side in contact with the transport belt 21 is referred to as surface PB.

[0063] As shown in Figures 2 and 3, the first transfer section 74 is composed of a backup roll 42, a secondary transfer roll 24, and a first intermediate transfer belt 40. The second transfer section 76 is composed of a backup roll 62, a secondary transfer roll 25, and a second intermediate transfer belt 60.

[0064] The secondary transfer rolls 24 and 25 rotate in conjunction with the rotation of the conveyor belt 21. Furthermore, a transfer bias is applied to the secondary transfer rolls 24 and 25 by the power supply unit 99 (see Figure 4).

[0065] The secondary transfer position TJ2 is defined as the space between the first intermediate transfer belt 40 and the transport belt 21 of the image forming unit 30, and the secondary transfer position TK2 is defined as the space between the second intermediate transfer belt 60 and the transport belt 21 of the image forming unit 50. Note that the secondary transfer position TK2 is the furthest downstream secondary transfer position.

[0066] Furthermore, the conveyor belt device 20 is equipped with a belt cleaning device (not shown) for cleaning the conveyor belt 21. The belt cleaning device (not shown) performs cleaning on the upstream side in the rotational direction of the furthest downstream secondary transfer position TK2 and on the downstream side in the rotational direction of the furthest upstream secondary transfer position TJ2.

[0067] [Main part configuration] Next, the configuration of the main parts of this embodiment will be explained, although some of it will be repeated.

[0068] As shown in Figures 2 and 3, in this embodiment, the second image forming group 51, which is composed of multiple image forming sections 52 of the image forming unit 50, is located downstream in the transport direction of the first image forming group 31, which is composed of multiple image forming sections 32 of the image forming unit 30. The first intermediate transfer belt 40 is provided downstream in the transport direction of the first image forming group 31. The second intermediate transfer belt 60 is provided upstream in the transport direction of the second image forming group 51. From another perspective, the first intermediate transfer belt 40 and the second intermediate transfer belt 60 are provided side by side in the transport direction between the first image forming group 31 and the second image forming group 51, which are aligned in the transport direction. Note that the first intermediate transfer belt 40 and the second intermediate transfer belt 60 are provided independently and are not shared.

[0069] The conveyor belt 21 is wrapped around the tension roll 22 and the drive roll 23 and is taut in the conveying direction. The distance L1 between the first transfer section 74 and the second transfer section 76 on the conveyor belt 21 is set to an integer multiple of the circumferential length L2 of the circumferential surface 23A of the drive roll 23, which in this embodiment is set to an equal multiple. That is, L1 = L2.

[0070] Furthermore, if L1 falls within ±0.3% of L2, it is considered to be the same scale. Also, if L1 falls within ±0.3% of an integer multiple of L2, it is considered an integer multiple.

[0071] The first intermediate transfer belt 40 is stretched in a direction that intersects the transport path 19 (see also Figure 1), with the X direction as its longitudinal direction in this embodiment. The multiple image forming units 32 constituting the first image forming group 31 are arranged in a longitudinal direction upstream of the first intermediate transfer belt 40 in the transport direction. The second intermediate transfer belt 60 is stretched in a direction that intersects the transport path 19 (see also Figure 1), with the X direction as its longitudinal direction in this embodiment. In other words, the multiple image forming units 52 constituting the second image forming group 51 are arranged in a longitudinal direction downstream of the second intermediate transfer belt 60 in the transport direction.

[0072] To explain from another perspective, the first intermediate transfer belt 40 and the second intermediate transfer belt 60 are arranged in a longitudinal direction in the direction that intersects the transport path 19, in this embodiment the X direction, when viewed from the Z direction, which is the rotation axis direction of the first intermediate transfer belt 40 and the second intermediate transfer belt 60, and are arranged parallel or substantially parallel to the Y direction.

[0073] As shown in Figure 3, the image forming unit 30 has a first cleaning blade 110 as an example of a first cleaning member for cleaning the first intermediate transfer belt 40. The first cleaning blade 110 is positioned to clean the portion of the first intermediate transfer belt 40 that is wrapped around the support roll 44, which is the longitudinal folded end of the first intermediate transfer belt 40 after secondary transfer.

[0074] Furthermore, the image forming unit 50 has a second cleaning blade 120 as an example of a second cleaning member for cleaning the second intermediate transfer belt 60. The second cleaning blade 120 is positioned to clean the space between the second transfer section 76 and the image forming section 52K of the second image forming group 51 after secondary transfer of the second intermediate transfer belt 60.

[0075] From another perspective, the first cleaning blade 110 and the second cleaning blade 120 are not located between the first intermediate transfer belt 40 and the second intermediate transfer belt 60.

[0076] Furthermore, as shown in Figures 2 and 3, an electrical circuit board 100, on which a control device 80 and a power supply device 99 (see Figure 4), etc., which will be described later, is provided on the upstream side in the transport direction of the first image forming group 31, at the lower end portion of the image forming apparatus 10 in this embodiment.

[0077] Thus, the first image forming group 31, the second image forming group 51, the first cleaning blade 110, the second cleaning blade 120, and the electrical substrate 100 are not provided between the first intermediate transfer belt 40 and the second intermediate transfer belt 60. Therefore, the distance between the first transfer section 74 and the second transfer section 76, which are aligned in the transport direction, is narrow.

[0078] [Control device] Next, using Figure 6, we will describe the control device 80 that controls the operation of the image forming apparatus 10.

[0079] As shown in Figure 6, the control device 80 is electrically connected to the image forming unit 30, the image forming unit 50, the communication unit 90, the non-volatile memory 92, and the power supply unit 99, among others.

[0080] The control unit 80 has a CPU 81 (Central Processing Unit), ROM 82 (Read Only Memory), RAM 83 (Random Access Memory), and input / output interface (I / O) 84, all connected via a bus.

[0081] Here, ROM 82 stores an image formation control program (not shown) that is to be executed by CPU 81. The CPU 81 then reads the image formation control program (not shown) from ROM 82 and loads it into RAM 83, thereby executing the printing process according to the image formation control program (not shown).

[0082] Furthermore, the I / O 84 is connected to the image forming unit 30, the image forming unit 50, the communication unit 90, and the non-volatile memory 92. The communication unit 90 is an interface for data communication between the image forming apparatus 10 and a terminal device such as a personal computer (not shown). The non-volatile memory 92 stores information necessary for the image forming apparatus 10 to perform image forming operations.

[0083] The control device 80 performs various controls to form toner images on the first intermediate transfer belt 40 (see Figure 2, etc.) using the image forming sections 32 (see Figure 2, etc.) of each color of the image forming unit 30. Similarly, it performs various controls to form toner images on the second intermediate transfer belt 60 (see Figure 2, etc.) using the image forming sections 52 (see Figure 2, etc.) of each color of the image forming unit 50.

[0084] Furthermore, the control device 80 controls the development bias applied to the development rolls 39Y, 39M, 39C, 39W, 59T, 59S, 59G, and 59K (see Figure 2, etc.) of the development units 36 and 56 by the power supply unit 99. In addition, the control device 80 controls the transfer bias applied to the secondary transfer rolls 24 and 25 (see Figure 2, etc.) by the power supply unit 99.

[0085] [Image forming process] Next, an overview of the image forming process in the image forming apparatus 10 will be described.

[0086] First, the control device 80 controls each image forming unit 32 so that a toner image is formed on the first intermediate transfer belt 40 of the image forming unit 30. Similarly, it controls each image forming unit 52 so that a toner image is formed on the second intermediate transfer belt 60 of the image forming unit 50.

[0087] Specifically, the control device 80 applies a voltage to the photoreceptor charging members 34 and 54, and charges the circumferential surfaces of the photoreceptors 33 and 53 to a predetermined potential using the voltage applied to the photoreceptor charging members 34 and 54. Subsequently, based on the image data acquired via the communication unit 90, the control device 80 irradiates the circumferential surfaces of the photoreceptors 33 and 53, which have been charged by the photoreceptor charging members 34 and 54, with exposure devices 35 and 55 to form an electrostatic latent image. As a result, an electrostatic latent image corresponding to the image data is formed on the circumferential surfaces of the photoreceptors 33 and 53.

[0088] Next, the control device 80 develops the electrostatic latent image formed by the exposure devices 35 and 55 using the developing devices 36 and 56, and visualizes it as a toner image. Furthermore, the control device 80 uses the primary transfer rolls 37 and 57 to transfer the toner images formed on the circumferential surfaces of the photoreceptors 33 and 53 of each color onto the first intermediate transfer belt 40 and the second intermediate transfer belt 60.

[0089] In this way, the image forming unit 30 forms a toner image on the first intermediate transfer belt 40 by superimposing, for example, yellow (Y), magenta (M), cyan (C), and white (W) toners. Similarly, the image forming unit 50 forms a toner image on the second intermediate transfer belt 60 by superimposing, for example, black (K), gold (G), silver (S), and transparent (T) toners.

[0090] Here, the recording paper P, which has been sent from the storage unit 12 to the transport path 19 by the delivery roll 13, is sent to the secondary transfer position TJ2 upstream in the transport direction after the transport timing is adjusted by the register roll pair 15 based on the control of the control device 80. At this secondary transfer position TJ2, the recording paper P is transported between the backup roll 42 and the secondary transfer roll 24, and the toner image on the outer surface of the first intermediate transfer belt 40 is transferred to the recording paper P. Then, the recording paper P with the transferred toner image is transported downstream in the transport direction to the secondary transfer position TK2 downstream in the transport direction.

[0091] At this time, the control device 80 adjusts the timing of starting image formation so that the toner image formed on the second intermediate transfer belt 60 of the image forming unit 50 is superimposed and transferred onto the toner image on the recording paper P that has been transported from the upstream side in the transport direction.

[0092] The recording paper P, on which the toner images of each color formed by the image forming unit 30 and the image forming unit 50 are superimposed and transferred, is fixed by the fixing roll pair 16 of the fixing device 18, and then discharged by the discharge roll 17 to the discharge section 9 located at the top of the main body 10A of the image forming device.

[0093] [Effect] Next, the operation of this embodiment will be described.

[0094] The second image forming group 51, which consists of multiple image forming sections 52 of the image forming unit 50, is located downstream in the transport direction of the first image forming group 31, which consists of multiple image forming sections 32 of the image forming unit 30. The first intermediate transfer belt 40 is provided downstream in the transport direction of the first image forming group 31. The second intermediate transfer belt 60 is provided upstream in the transport direction of the second image forming group 51. In other words, the first image forming group 31 and the second image forming group 51 are not located between the first intermediate transfer belt 40 and the second intermediate transfer belt 60. Therefore, the space between the first transfer section 74 and the second transfer section 76 in the transport path 19 can be narrowed compared to the case where there are image forming sections 32 and 52 between the first intermediate transfer belt 40 and the second intermediate transfer belt 60 which are aligned in the transport direction.

[0095] In this way, by narrowing the space between the two first transfer units 74 and the second transfer unit 76, which are aligned in the transport direction, the separation of the recording paper P being transported between them from the transport path 19 is suppressed. Therefore, the misalignment of the toner image in the second transfer unit 76 caused by the separation of the recording paper P being transported between the two first transfer units 74 and the second transfer unit 76, which are aligned in the transport direction, from the transport path 19 is suppressed.

[0096] Furthermore, the conveyor belt 21 is wrapped around the tension roll 22 and the drive roll 23 and is taut in the conveying direction. The distance L1 between the first transfer section 74 and the second transfer section 76 on the conveyor belt 21 is set to an integer multiple of the circumferential length L2 of the circumferential surface 23A of the drive roll 23, and in this embodiment, it is set to an equal multiple (L1=L2).

[0097] Therefore, the effect of rotational unevenness of the drive roll 23 is smaller compared to the case where the distance L1 between the first transfer section 74 and the second transfer section 76 on the conveyor belt 21 is not an integer multiple of the circumferential length L2 of the circumferential surface 23A of the drive roll 23. Specifically, if it is an integer multiple, the effect of rotational unevenness at the first transfer section 74 is canceled out at the second transfer section 76, so the effect of rotational unevenness of the drive roll 23 is reduced.

[0098] Furthermore, since the distance L1 between the first transfer section 74 and the second transfer section 76 on the conveyor belt 21 is equal to the circumferential length L2 of the circumferential surface 23A of the drive roll 23, the distance between the first transfer section 74 and the second transfer section 76 becomes narrower compared to the case where it is twice or more.

[0099] Furthermore, the first intermediate transfer belt 40 is stretched in a direction intersecting the transport path 19, with the X direction being its longitudinal direction in this embodiment. Therefore, compared to the case where the first intermediate transfer body is a drum instead of a belt, the space between the first transfer section 74 and the second transfer section 76 in the transport path 19 can be narrowed.

[0100] Furthermore, the second intermediate transfer belt 60 is stretched in a direction intersecting the transport path 19, with the X direction being its longitudinal direction in this embodiment. Therefore, compared to the case where the second intermediate transfer body is a drum instead of a belt, the space between the first transfer section 74 and the second transfer section 76 in the transport path 19 can be narrowed.

[0101] Furthermore, the first cleaning blade 110 is positioned to clean the portion of the first intermediate transfer belt 40 that is wrapped around the support roll 44, which is the longitudinal folded end of the first intermediate transfer belt 40 after secondary transfer. Therefore, compared to the case where the first cleaning blade 110 is located between the first intermediate transfer belt 40 and the second intermediate transfer belt 60, the distance between the first intermediate transfer belt 40 and the second intermediate transfer belt 60 can be narrowed, and thus the distance between the first transfer section 74 and the second transfer section 76 in the transport path 19 can be narrowed.

[0102] Furthermore, the second cleaning blade 120 is provided between the second transfer section 76 and the image forming section 52K of the second image forming group 51 after secondary transfer on the second intermediate transfer belt 60. Compared to the case where the second cleaning blade 120 is located between the first intermediate transfer belt 40 and the second intermediate transfer belt 60, the distance between the first intermediate transfer belt 40 and the second intermediate transfer belt 60 can be narrowed, thus narrowing the distance between the first transfer section 74 and the second transfer section 76 in the transport path 19.

[0103] Furthermore, an electrical substrate 100, on which a control device 80 and a power supply device 99 are provided, is located upstream of the first image forming group 31 in the transport direction, at the lower end of the image forming apparatus 10 in this embodiment. Therefore, compared to the case where the electrical substrate 100 is located between the first intermediate transfer belt 40 and the second intermediate transfer belt 60, the gap between the first intermediate transfer belt 40 and the second intermediate transfer belt 60 can be narrowed, thus narrowing the gap between the first transfer section 74 and the second transfer section 76 in the transport path 19.

[0104] <Second Embodiment> Next, an image forming apparatus according to the second embodiment of the present invention will be described. Note that the configuration is the same as the first embodiment, except for the difference in the distance between the first transfer section 74 and the second transfer section 76. Therefore, further explanation will be omitted or simplified.

[0105] [Main part configuration] The main components of this embodiment will now be described.

[0106] In the image forming apparatus 200 of this embodiment shown in Figure 4, the minimum width LS is defined as the width in the transport direction of the smallest recording paper PS. In this embodiment, the minimum width LS is the width of the shorter side of an A5 size recording paper PS when it is fed horizontally. In other words, in this embodiment, the minimum width LS is the width of the shorter side of an A5 size.

[0107] Furthermore, the distance L3 between the first transfer section 74 and the second transfer section 76 is less than the minimum width LS. The distance L1 is the distance between the axes of the secondary transfer rolls 24 and 25.

[0108] [Effect] Next, the operation of this embodiment will be described.

[0109] Since the distance L3 between the first transfer unit 74 and the second transfer unit 76 is less than the minimum width LS, when a recording paper PS of the minimum width LS is being transported, the recording paper PS is covered by both the first transfer unit 74 and the second transfer unit 76.

[0110] Therefore, compared to the case where the distance L3 between the first transfer unit 74 and the second transfer unit 76 is greater than the minimum width LS, the separation of the recording paper PS from the transport path 19 is suppressed.

[0111] <Reference example> An example of an image forming apparatus will be described.

[0112] [composition] First, let's explain the structure of the example.

[0113] The reference example image forming apparatus 910 shown in Figure 5 includes an image forming unit 30 and an image forming section 900, etc., which form a toner image to be transferred to the recording paper P. The image forming unit 30, other control devices 80 and conveyor belt device 20, etc., are the same as those in the first and second embodiments described above, so their explanation will be omitted.

[0114] The image forming unit 900 is located in the same place as the image forming unit 50 (see Figures 3 and 4) in the first and second embodiments. It comprises a photoreceptor 908, a photoreceptor charging member 906, an exposure device 904, and a developing device 902. The developing device 902 has a developing roll 901 to which a developing bias is applied. In this embodiment, the image forming unit 900 forms a black (K) toner image.

[0115] The first intermediate transfer belt 40 is provided on the downstream side of the first image forming group 31 in the transport direction. Furthermore, the distance L4 between the first transfer section 74 and the second transfer section 76 on the transport belt 21 is equal to the circumferential length L2 of the circumferential surface 23A of the drive roll 23 (L4=L2) or less than the minimum width LS.

[0116] [Image forming process] Next, an overview of the image forming process in the image forming apparatus 910 will be described.

[0117] First, the control device 80 controls each image forming unit 32 so that a toner image is formed on the first intermediate transfer belt 40 of the image forming unit 30. Similarly, it controls the photoreceptor 908 of the image forming unit 900 so that a toner image is formed on it.

[0118] Next, we will explain the specific image formation process. However, the formation of the toner image on the first intermediate transfer belt 40 of the image formation unit 30 is the same as in the first and second embodiments described above, so we will omit the explanation.

[0119] The control device 80 applies a voltage to the photoreceptor charging member 906, and the voltage applied to the photoreceptor charging member 906 charges the circumferential surface of the photoreceptor 908 to a predetermined potential. Subsequently, based on the image data acquired via the communication unit 90, the control device 80 irradiates the circumferential surface of the photoreceptor 908, which has been charged by the photoreceptor charging member 906, with exposure using the exposure device 904 to form an electrostatic latent image. As a result, an electrostatic latent image corresponding to the image data is formed on the circumferential surface of the photoreceptor 908.

[0120] Next, the control device 80 uses the developing device 902 to develop the electrostatic latent image formed by the exposure device 904 and visualize it as a toner image.

[0121] In this way, a toner image is formed on the first intermediate transfer belt 40 in the image forming unit 30, for example, by superimposing yellow (Y), magenta (M), cyan (C), and white (W) toners. Similarly, a black (K) toner image is formed on the photoreceptor 908 of the image forming unit 900.

[0122] Here, the recording paper P, which has been sent from the storage unit 12 to the transport path 19 by the delivery roll 13, is sent to the secondary transfer position TJ2 upstream in the transport direction after the transport timing is adjusted by the register roll pair 15 based on the control of the control device 80. At this secondary transfer position TJ2, the recording paper P is transported between the backup roll 42 and the secondary transfer roll 24, and the toner image on the outer surface of the first intermediate transfer belt 40 is transferred to the recording paper P. Then, the recording paper P with the transferred toner image is transported downstream in the transport direction to the secondary transfer position TK2 downstream in the transport direction.

[0123] At this time, the control device 80 adjusts the timing for starting image formation so that the toner image formed on the photoreceptor 908 of the image forming unit 900 is superimposed and transferred onto the toner image on the recording paper P that has been transported from the upstream side in the transport direction.

[0124] The recording paper P, on which the toner images of each color formed by the image forming unit 30 and the image forming section 900 are superimposed and transferred, is fixed by the fixing roll pair 16 of the fixing device 18, and then discharged by the discharge roll 17 to the discharge section 9 located at the top of the main body 10A of the image forming device.

[0125] [Effect] The first intermediate transfer belt 40 is provided downstream of the first image forming group 31 in the transport direction, and the first image forming group 31 is not provided between the first intermediate transfer belt 40 and the photoreceptor 908. Therefore, compared to the case where the first image forming group 31 is located downstream of the first intermediate transfer belt 40 in the transport direction, the space between the first transfer section 74 and the second transfer section 76 in the transport path 19 can be narrowed.

[0126] Furthermore, by narrowing the space between the two first transfer units 74 and the second transfer unit 76, which are aligned in the transport direction, the separation of the recording paper P from the transport path 19 as it is transported between them is suppressed. Therefore, the misalignment of the toner image in the second transfer unit 76 caused by the separation of the recording paper P from the transport path 19 as it is transported between the two first transfer units 74 and the second transfer unit 76, which are aligned in the transport direction, is suppressed.

[0127] When the distance L4 between the first transfer section 74 and the second transfer section 76 on the conveyor belt 21 is equal to the circumferential length L2 of the circumferential surface 23A of the drive roll 23 (L4=L2), the effect of rotational unevenness of the drive roll 23 is smaller, and the distance between the first transfer section 74 and the second transfer section 76 can be narrowed, compared to the case where the distance L4 is not an integer multiple of the circumferential length L2 of the circumferential surface 23A of the drive roll 23.

[0128] Furthermore, when the distance L4 between the first transfer unit 74 and the second transfer unit 76 is less than the minimum width LS, the separation of the recording paper PS from the transport path 19 is suppressed compared to when the distance L4 is greater than the minimum width LS.

[0129] <Other> Furthermore, the present invention is not limited to the embodiments described above.

[0130] For example, in the above embodiment, in the first embodiment, the distance L1 between the first transfer section 74 and the second transfer section 76 on the conveyor belt 21 was equal to the circumferential length L2 of the circumferential surface 23A of the drive roll 23 (L1 = L2), but it may be an integer multiple of 2 or more. Note that even if L1 is an integer multiple of 2 or more of L2, it is preferable because the effect of rotational unevenness of the drive roll 23 is small. However, it is not limited to L1 being an integer multiple of L2.

[0131] Furthermore, for example, in the above embodiment, in the second embodiment, the distance L3 between the first transfer section 74 and the second transfer section 76 on the transport belt 21 was less than the minimum width LS, but it may be less than or equal to the minimum width LS. Even if L3 is the same as LS, the separation of the recording paper PS from the transport path 19 is suppressed. However, it is not limited to L3 being less than or equal to LS.

[0132] Furthermore, for example, the distance between the first transfer section 74 and the second transfer section 76 on the conveyor belt 21 may be equal to the circumferential length of the circumferential surface 23A of the drive roll 23 and less than the minimum width LS.

[0133] Furthermore, in the above embodiment, for example, the first cleaning blade 110 is positioned to clean the portion of the first intermediate transfer belt 40 that is wrapped around the support roll 44, which is the longitudinal folded end of the first intermediate transfer belt 40 after secondary transfer, but it is not limited to this. The first cleaning blade 110 may also clean the area between the portion of the first intermediate transfer belt 40 that is wrapped around the support roll 44, which is the longitudinal folded end of the first intermediate transfer belt 40 after secondary transfer, and the image forming section 32Y of the first image forming group 31.

[0134] Furthermore, in the above embodiment, the first intermediate transfer belt 40 was cleaned with the first cleaning blade 110, but this is not limited to that. For example, the first intermediate transfer belt 40 may be cleaned with a brush.

[0135] Furthermore, for example, in the above embodiment, the second intermediate transfer belt 60 was cleaned with the second cleaning blade 120, but this is not limited to that. For example, the second intermediate transfer belt 60 may be cleaned with a brush.

[0136] Furthermore, although the image forming units 30 and 50 in the above embodiment each had four image forming sections 32 and 52, they are not limited to this. An image forming unit only needs to have two or more image forming sections.

[0137] Furthermore, in the above embodiment, for example, the image forming apparatus 10 was equipped with two image forming units, an image forming unit 30 and an image forming unit 50, but it is not limited to this. An image forming apparatus may be equipped with three or more image forming units.

[0138] Furthermore, in the above embodiment, the electrical substrate 100 is located upstream of the first image forming group 31 in the transport direction, but this is not the only possible configuration. The electrical substrate 100 may also be located downstream of the second image forming group 51 in the transport direction.

[0139] Furthermore, for example, in the above embodiment, the recording medium was recording paper P such as plain paper, but it is not limited to this. The recording medium may also be a sheet-like material such as an OHP.

[0140] Furthermore, in the above embodiment, for example, the conveying means that contacts and conveys one side of the recording medium was a conveying belt 21, but it is not limited to this. The conveying means may be something other than a belt, such as a drum.

[0141] Furthermore, in the above embodiment, for example, the first intermediate transfer body and the second intermediate transfer body to which the toner image is first transferred were the first intermediate transfer belt 40 and the second intermediate transfer belt 60, but the invention is not limited to these. The first intermediate transfer body and the second intermediate transfer body may be other than belts, for example, a drum.

[0142] Furthermore, the configuration of the image forming apparatus is not limited to the configuration of the above embodiment, and various configurations are possible. Moreover, the present invention can be implemented in various forms without departing from the spirit of the invention. [Explanation of Symbols]

[0143] 10 Image forming apparatus 19. Transport Route 21. Conveyor belt (an example of a conveying means) 31 Image Forming Group 32 Image forming unit 40. Intermediate transfer belt (an example of an intermediate transfer material) 51 Image-forming group 52 Image forming unit 60 Intermediate transfer belt (an example of an intermediate transfer material) 74 Secondary transfer section 76 Secondary transfer section 100 Electrical circuit boards 110 First cleaning blade (an example of the first cleaning component) 120 Second cleaning blade (an example of a second cleaning component) P Recording sheet (an example of a recording medium) PA surface (the other surface) PB side (one side) PS recording paper (an example of the smallest recording medium capable of forming an image)

Claims

1. A transport means for transporting a recording medium along a transport path while in contact with one side of the recording medium, A first image forming group is provided on the other side of the recording medium in the transport path and consists of a plurality of image forming units that form a toner image, A second image forming group is provided on the downstream side of the transport direction of the first image forming group on the other side of the recording medium in the transport path, and is composed of a plurality of image forming units that form a toner image, A first intermediate transfer body is provided on the downstream side in the transport direction of the first image forming group, and the toner images formed by the plurality of image forming units of the first image forming group are transferred to it as a primary transfer, A second intermediate transfer body is provided on the upstream side in the transport direction of the second image forming group, and the toner images formed by the plurality of image forming units of the second image forming group are transferred to it as a primary transfer, A first transfer unit that secondarily transfers the toner image from the first intermediate transfer body to the other surface of the recording medium transported by the transport means, A second transfer unit that secondarily transfers the toner image from the second intermediate transfer body to the other surface of the recording medium transported by the transport means, An image forming apparatus equipped with [a specific feature].

2. The conveying means is a conveying belt wrapped around a tensioned roll and a drive roll, The distance between the first transfer section and the second transfer section in the conveyor belt is set to an integer multiple of the circumferential length of the drive roll. The image forming apparatus according to claim 1.

3. The distance between the first transfer section and the second transfer section in the conveyor belt and the circumferential length of the drive roll are set to be the same length. The image forming apparatus according to claim 2.

4. The distance between the first transfer unit and the second transfer unit is set to be less than or equal to the minimum width in the transport direction of the recording medium that can form an image. The image forming apparatus according to claim 1.

5. The distance between the first transfer unit and the second transfer unit is set to be smaller than the minimum width in the transport direction of the recording medium that can form an image. The image forming apparatus according to claim 4.

6. The first intermediate transfer body is a first intermediate transfer belt stretched with its longitudinal direction intersecting the transport path when viewed from the side in the direction of the rotation axis. The plurality of image forming units constituting the first image forming group are arranged in the longitudinal direction on the upstream side in the transport direction of the first intermediate transfer belt, The image forming apparatus according to any one of claims 1 to 5.

7. It has a first cleaning member for cleaning the first intermediate transfer belt, The first cleaning member is provided at a position to clean the longitudinal folded end of the first intermediate transfer belt after secondary transfer, or the space between the folded end and the first image forming group. The image forming apparatus according to claim 6.

8. The second intermediate transfer body is a second intermediate transfer belt stretched with its longitudinal direction intersecting the transport path when viewed from the side in the direction of the rotation axis. The plurality of image forming units constituting the second image forming group carry the second intermediate transfer belt Arranged in the longitudinal direction on the downstream side in the transmission direction, The image forming apparatus according to any one of claims 1 to 7.

9. It has a second cleaning member for cleaning the second intermediate transfer belt, The second cleaning member is positioned to clean the space between the second transfer section and the second image forming group after the secondary transfer of the second intermediate transfer belt. The image forming apparatus according to claim 8.

10. An electrical substrate is positioned on the upstream side in the transport direction of the first image forming group or on the downstream side in the transport direction of the second image forming group. The image forming apparatus according to any one of claims 1 to 9.

Images