Image forming system

Abstract

A sheet-folding device 200 provided in an in-body space 50 of an image forming apparatus 100 receives a sheet Sh from a second discharge port 33 disposed vertically above a first discharge port 31 of the image forming apparatus 100, and performs a Z-folding process while conveying the sheet Sh downward using a folding mechanism 210. The height position where the sheet-folding device 200 receives the sheet Sh is high; therefore, due to the sheet Sh being received not from the first discharge port 31 but from the second discharge port 33, a run-up path connecting the first discharge port 31 to the first reception port 201 is unnecessary, and the width size of the sheet-folding device 200 is compact.

Description

Image forming system Field of Application of the Invention

[0001] The present invention relates to an image forming system including a sheet processing apparatus that performs a folding process on sheets discharged from an image forming apparatus. Description of Related Art

[0002] Conventionally, there has been known an image forming apparatus provided with a first discharge port for discharging a sheet having an image formed by an image forming section toward an in-body space (a space formed between the image forming section and a reading section), and a second discharge port vertically above the first discharge port for discharging a sheet toward the in-body space, wherein sheets can be discharged from the respective discharge ports and stacked (Japanese Patent Laid-Open No. 2009-294268).

[0003] An image forming apparatus having such an in-body space is configured such that an in-body sheet processing apparatus that performs post-processing such as binding processing and folding processing on a sheet on which an image is formed can be mounted thereon. Conventionally, the in-body sheet processing apparatus receives sheets discharged from a first discharge port of the image forming apparatus and performs post-processing thereon.

[0004] As one type of in-body sheet processing apparatus, an in-body folding apparatus that performs a folding process on a sheet is known (Japanese Patent Laid-Open No. 2022-37635). This in-body folding apparatus discharges Z-folded (outer three-folded) sheets face-down (discharged with the first fold positioned below the sheet and the second fold positioned at the leading end of the sheet), and as a folding mechanism for folding sheets, the apparatus comprises: a receiving section that receives sheets discharged from the first discharge port; a first folding roller pair that forms a first fold while conveying the received sheet vertically downward; and a second folding roller pair that forms a second fold closer to the trailing end side of the sheet than the first fold while conveying the sheet to the left when viewed from the front of the apparatus, the sheet having been folded by the first folding roller pair.

[0005] Because the aforementioned folding mechanism has a height difference from the receiving section that receives the sheet to the nip section of the second folding roller pair, it is desirable to position the receiving section above the first discharge port of the image forming apparatus within the internal space of the machine body. As a result, the internal folding device requires an upward path to connect the sheet received from the first discharge port to the receiving section of the folding mechanism. Consequently, the width of the internal folding device (the width in the left-right direction when viewed from the front) becomes larger by the amount of this upward path.

[0006] The present invention relates to an image forming system comprising an image forming apparatus for forming an image on a sheet and a sheet folding apparatus for folding a sheet received from the image forming apparatus, wherein the image forming apparatus comprises an image forming unit for forming an image on a sheet, a reading unit positioned above the image forming unit for reading an image from a document, a first discharge port from which the sheet on which the image has been formed by the image forming unit is discharged toward an internal space formed between the image forming unit and the reading unit, and a second discharge port positioned vertically above the first discharge port from which the sheet on which the image has been formed is discharged toward the internal space, and the sheet folding apparatus is provided in the internal space of the cylinder. The sheet folding device is characterized by comprising: a receiving section that receives sheets discharged from the second discharge port located vertically above the first discharge port; a pair of first folding rollers that make a first fold while conveying the sheet received in the receiving section vertically downward; a folding mechanism that has a pair of second folding rollers that make a second fold on the rear end side of the sheet, while conveying the sheet folded by the pair of first folding rollers in a direction toward the receiving section from the second discharge port, and is capable of performing a Z-fold on the sheet so that the first fold is on the lower surface side of the sheet; and a conveying mechanism that conveys the sheet received from the first discharge port without passing through the folding mechanism.

[0007] Furthermore, the present invention relates to an image forming system comprising an image forming apparatus for forming an image on a sheet and a sheet folding apparatus for performing a folding process on a sheet received from the image forming apparatus, wherein the image forming apparatus includes an image forming unit for forming an image on a sheet, a sheet reversing unit for receiving the sheet on which the image has been formed by the image forming unit from the rear end of the sheet and transporting the sheet back to the image forming unit, a reading unit positioned above the image forming unit for reading an image from a document, a first discharge port from which the front end of the sheet is discharged toward the internal space formed between the image forming unit and the reading unit until the rear end of the sheet on which the image has been formed by the image forming unit can be received by the sheet reversing unit, and a front section positioned vertically above the first discharge port. The sheet folding device is provided in the internal space of the cylinder and is characterized by comprising: a second discharge port from which a sheet on which an image has been formed by the image forming unit is discharged toward the internal space of the cylinder; a receiving section located vertically above the first discharge port for receiving a sheet discharged from the second discharge port; a pair of first folding rollers that convey the sheet received in the receiving section vertically downward while making a first fold; and a pair of second folding rollers that convey the sheet folded by the pair of first folding rollers toward the receiving section from the second discharge port while making a second fold on the rear end side of the sheet beyond the first fold, and a folding mechanism capable of performing a Z-fold on the sheet such that the first fold is on the lower surface side of the sheet.

[0008] Further features of the present invention will become apparent from the following description of exemplary embodiments, which will be explained in conjunction with the accompanying drawings.

[0009] This is a cross-sectional view of an image forming system.

[0010] This is a perspective view of an image forming apparatus.

[0011] This is a cross-sectional view of the internal space of the image forming apparatus and the internal folding mechanism.

[0012] (a) to (c) are diagrams illustrating the register process for each sheet.

[0013] (a) to (c) are diagrams illustrating the process of inverting a sheet.

[0014] (a) to (d) are diagrams illustrating the process of overlapping sheets.

[0015] (a) to (c) are diagrams illustrating the Z-fold (outer tri-fold) process for the sheet.

[0016] (a) to (c) are diagrams illustrating the process of folding a sheet into a C-fold (inner tri-fold).

[0017] (a) and (b) are diagrams illustrating the V-fold (fold in half) process for a sheet.

[0018] This is a cross-sectional view of the internal folding device, showing the state in which the sheet received from the first discharge port of the image forming apparatus is being conveyed through without being folded.

[0019] This is a cross-sectional view of the image forming apparatus with an internal folding device and an internal finisher installed in the internal space of the apparatus body.

[0020] This is a block diagram of an image forming system.

[0021] This is a cross-sectional view showing a modified image forming apparatus. Description of the Embodiment

[0022] Hereinafter, an embodiment of the image forming system according to the present invention will be specifically described with reference to the drawings. Note that the dimensions, materials, and relative positions of each component of the image forming system shown below do not limit the scope of the present invention to those components unless otherwise specifically stated. Furthermore, components denoted by the same reference numerals in each figure have the same configuration or function, and redundant explanations of these components will be omitted as appropriate.

[0023] In the following explanation, the upward U, downward D, rightward R, leftward L, rearward B, and forward F directions shown in Figures 1-3 and 10, 11, and 13 are defined as follows: The side of the image forming apparatus 100 shown in Figures 1, 2, and 13 where the operating unit 11 is located is defined as the front side (front or front), and the opposite side is defined as the rear side (back or back). In Figure 1, the direction from the back of the paper to the front is defined as the forward direction, and the direction from the front of the paper to the back is defined as the rear direction. Furthermore, when the image forming unit UK that forms the black image is used as a reference, the side where the image forming unit UY that forms the yellow image is located is defined as the left side. When the image forming unit UY that forms the yellow image is used as a reference, the side where the image forming unit UK that forms the black image is located is defined as the right side. Furthermore, the direction perpendicular to the front-back and left-right directions defined here, and vertically upward, is defined as the upward direction, and the direction perpendicular to the front-back and left-right directions defined here, and vertically downward, is defined as the downward direction.

[0024] The image forming system 1000 of this embodiment consists of an image forming apparatus 100 equipped with a paper feeding unit 23, an image forming unit 1 (as an image forming section), and a reading unit 40, and an in-body folding device 200 (or an in-body finisher 300 as shown in Figure 11, if necessary) mounted in the in-body space 50 formed between the image forming unit 1 and the reading unit 40.

[0025] (Image forming apparatus) The image forming apparatus 100 will be described using Figure 1. Figure 1 is a schematic cross-sectional view of the image forming apparatus 100 in this embodiment, taken from the front.

[0026] The image forming apparatus 100 shown in Figure 1 is a tandem-intermediate transfer type four-color full-color laser printer using an electrophotographic process, and is an example of an image forming apparatus. The image forming apparatus 100 forms a toner image on a sheet Sh based on image information input to a control circuit unit (not shown) from an external host device 400 such as a personal computer, and image information of a document read by a reading unit 40.

[0027] The image forming apparatus 100 has an image forming unit 1 located approximately in the center of the apparatus, which sequentially forms toner images of four colors: yellow (Y), magenta (M), cyan (C), and black (K), in that order from left to right.

[0028] The image forming units UY, UM, UC, and UK, which are part of the image forming unit 1 that forms toner images of each color, have a nearly identical configuration. To avoid complexity in the diagram, each component constituting the cyan image forming unit UC is given a reference numeral, while the reference numerals for the components constituting the other image forming units UY, UM, and UK are omitted.

[0029] The four image-forming units UY, UM, UC, and UK each consist of a drum unit equipped with a rotating drum-type electrophotographic photoreceptor (hereinafter referred to as the photosensitive drum) 2 as an image carrier, and a developing unit equipped with a developing sleeve 5 for developing the toner image. Each image-forming unit is configured to be replaceable or detachable from the front side of the image forming apparatus 100.

[0030] The drum unit comprises a photosensitive drum 2, a charging roller 3 for charging the photosensitive drum, and a drum cleaner section (not shown).

[0031] The developing unit includes a developing sleeve 5, as well as a screw (not shown) that supplies toner to the developing sleeve and agitates the toner.

[0032] An LED exposure unit 4 equipped with an LED light-emitting element is positioned between the drum unit and the developing unit.

[0033] Furthermore, an intermediate transfer belt unit 8 is positioned above the four image-forming units UY, UM, UC, and UK. The intermediate transfer belt unit 8 comprises four primary transfer rollers 6 and a belt 9, which are positioned opposite each color's photosensitive drum 2.

[0034] Toner bottles 22Y, 22M, 22C, and 22K are positioned on top of the intermediate transfer belt unit 8. These toner bottles contain replenishment toner for the four imaging units UY, UM, UC, and UK, and are removable and replaceable. As a result, the appropriate amount of toner is supplied to each color imaging unit UY, UM, UC, and UK from the corresponding toner bottle by a toner supply mechanism (not shown) in a timely manner.

[0035] Inside the image forming apparatus 100, a transport path 26 is provided to the right of the imaging units UY to UK, the intermediate transfer belt unit 8, and the toner bottles 22Y to 22K, through which the sheet S is transported from bottom to top. In this sheet transport path, a pair of registration rollers 25, a secondary transfer roller 16, a fixing unit 19, and several other pairs of transport rollers are arranged in order from bottom to top.

[0036] The secondary transfer roller 16 contacts the belt drive roller 10 on the right side of the intermediate transfer belt unit 8 via the belt 9 with a predetermined pressing force, forming a secondary transfer nip portion 17 with the belt 9, where the image is transferred to the sheet (the intermediate transfer belt 8, belt drive roller 10, and secondary transfer roller 16 are referred to as the transfer unit). The fixing unit 19 fixes the image to the sheet by applying heat and pressure to the sheet onto which the image has been transferred by the secondary transfer roller 16.

[0037] In this embodiment, the image formation units UY to UK and the transfer unit are collectively referred to as the image forming unit 1.

[0038] Furthermore, below the four imaging units UY, UM, UC, and UK, are a sheet cassette 23, a pick roller 24 that supplies sheets one by one from the sheet cassette 23, and a pair of register rollers 25 that correct the skew of the sheets received from the pick roller 24 and transport them at the appropriate timing (this set is called a paper feeding unit). Multiple sheet cassettes 23 are arranged vertically.

[0039] (Image forming process) In the image forming process, a latent image is formed on each photosensitive drum 2 of the four image forming units UY, UM, UC, and UK. As a preparatory operation, a high voltage is applied to the charging roller 3 pressed against the photosensitive drum 2, and the surface of the photosensitive drum 2 is uniformly charged as the photosensitive drum 2 rotates.

[0040] Next, a high voltage is applied to the developing sleeve 5 through a path different from that of the charging roller 3, so that the charged toner inside the developing unit is uniformly coated on the surface of the developing sleeve 5. Inside the developing unit, the toner is circulated and conveyed at high speed by a screw. The rotation speed of the screw 7 is relatively very high compared with the rotation speed of the developing sleeve 5 and the photosensitive drum 2, so that the coating on the developing sleeve 5 can be performed uniformly without unevenness.

[0041] Then, by means of the light emission and irradiation of the LEDs of the LED exposure unit 4 arranged between the drum unit and the developing unit, an electrostatic latent image is formed by potential change on the surface of the photosensitive drum 2, and the toner on the developing sleeve 5 develops the latent image on the photosensitive drum 2 into a toner image.

[0042] The toner image on the photosensitive drum is primarily transferred onto the surface of the belt 9, which is an intermediate transfer member, in the order of the respective colors in accordance with the rotation of the belt 9. As a result, a four-color superimposed toner image of Y+M+C+K is formed on the belt 9.

[0043] Here, the pick roller 24 is driven at a predetermined control timing, sheets (recording material, paper) Sh are separated and fed one by one from the sheet cassette 23, and introduced into the conveying path 26. Then, the sheet Sh is introduced into the secondary transfer nip portion 17 by the pair of registration rollers 25 at a predetermined control timing, and is nipped and conveyed. As a result, at the secondary transfer nip portion 17, the four-color superimposed toner image on the belt 9 is collectively secondarily transferred onto the sheet S, and an unfixed toner image is formed on the sheet Sh.

[0044] The sheet Sh exiting the secondary transfer nip 17 is introduced into the fixing unit 19 and undergoes a fixing process of the toner image by heat and pressure, whereby the image forming process on one surface of the sheet Sh is completed. The flapper 28 switches the conveyance path such that when the sheet Sh with an image formed thereon is discharged from the first discharge port 31 by the first discharge roller pair 30, the sheet is conveyed toward the first discharge path 27, and when the sheet is discharged from the second discharge port 33 by the second discharge roller pair 32 or conveyed to the reverse path 34, the sheet is conveyed toward the second discharge path 29. Hereinafter, the term flapper refers to a member that switches the sheet conveyance path by moving.

[0045] When image formation is performed on the second surface (back surface) of the sheet Sh, the flapper 28 guides the sheet Sh to the second discharge path 29, the leading edge of the sheet Sh is discharged from the second discharge port 33 by the second discharge roller pair 32, and when the trailing edge of the sheet passes the flapper 29, the flapper 35 is moved, and at the same time, the second discharge roller pair 32 is driven in reverse to guide the trailing edge of the sheet Sh to the reverse path 34. The sheet Sh guided to the reverse path 34 is guided to the conveyance path 26 from the trailing edge, and passes through the transfer unit 16 and the fixing unit 19 again, whereby an image is formed on the second surface of the sheet. In the present embodiment, the term path refers to a structure constituted by sheet guides on both sides that guide the sheet Sh when the sheet Sh conveyed by a conveyance roller pair or the like comes into contact therewith.

[0046] The sheet Sh on which an image is formed by the image forming unit 1 is discharged toward the in-body space 50 through the first discharge port 31 or the second discharge port 33. In the present embodiment, the first discharge port 31 and the second discharge port 32 are provided on the first side surface (discharge port arrangement surface) 53 which is one side surface forming the in-body space 50, and the second discharge port 33 is arranged vertically above the first discharge port 31. The first discharge roller pair 30 is configured to discharge the sheet Sh through the first discharge port 31 toward the left direction in FIG. 1 (a direction that is not horizontal but has a component in the direction of arrow L), and the second discharge roller pair 32 is configured to discharge the sheet Sh through the second discharge port 33 toward the same left direction in FIG. 1 (a direction that is not horizontal but has a component in the direction of arrow L).

[0047] As shown in Figure 2, the internal space 50 of this embodiment is formed by an internal lower surface 51 that covers a part of the image forming unit 1, an internal upper surface 52 located below the reading unit, and a first side surface 53 on which the first discharge port 31 and the second discharge port 33 are located. At least the front side of the image forming apparatus 100 (the side on which the operating unit 11 is located in the sheet width direction intersecting the direction in which the sheet Sh is discharged by the first and second discharge roller pairs 30 and 32) and the left side (the downstream side in the direction of the arrow component L in the direction in which the sheet Sh is discharged by the first and second discharge roller pairs 30 and 32; or, in Figure 3, when the internal folding device 200 is installed in the internal space 50, the side opposite the first side surface 53 to the internal folding device 200 in the left-right direction). In this embodiment, the second side surface 54, which is the rear side of the device, also forms part of the internal space 50. The second side may have connection parts (not shown), such as drawer connectors, for electrically connecting the internal folding device 200 and the internal finisher 300 (described later) to the image forming apparatus 100. The lower internal surface 51 is the mounting surface on which the internal folding device 200 and the internal finisher 300 are installed (supported).

[0048] Furthermore, the image forming apparatus 100 has a reading unit 40 positioned above the image forming unit 1 as a reading unit for reading the original document, and the image forming unit 1 performs image formation on the sheet based on the image information read by the reading unit 40. In other words, the internal space 50 is formed between the image forming unit 1 and the reading unit 40, and is a space enclosed by the internal lower surface 51, the first side surface 53 (one of the walls forming the internal space), the second side surface 54 (one of the walls forming the internal space), and the internal upper surface 52 which is the lower surface of the reading unit 40.

[0049] In this embodiment, the fixing unit 19 is shown positioned vertically below the lower surface 51 inside the cylinder. However, a part of the fixing unit 19 may be positioned to the right of the first side surface 53 and protruding above the lower surface 51 inside the cylinder. The internal space 50 inside the cylinder only needs to be formed between a part of the image forming unit 1 (image forming units UY to UK and the transfer unit) for forming an image on the sheet Sh in the vertical direction and the reading unit 40. Furthermore, each surface forming the internal space 50 inside the cylinder does not need to be flat; it may have irregularities or be composed of multiple parts. Also, the internal space inside the cylinder may be U-shaped without the second side surface 54. In addition, the image forming unit 1 in this embodiment is not limited to the electrophotographic method described above, and an inkjet method may be adopted.

[0050] (Sheet Processing Device) Here, we will describe a sheet processing device that can be attached to an image forming apparatus, specifically a sheet folding device (hereinafter referred to as a sheet folding device) 200. The sheet folding device 200 is installed in the internal space 50 of the image forming apparatus 100 and is a device that performs folding processes such as V-fold (fold in half), C-fold (fold in three inward), Z-fold (fold in three outward), and quad-fold on image-formed sheets received from the image forming apparatus 100.

[0051] The sheet folding device 200 of this embodiment includes a first receiving port 201 for receiving sheets Sh discharged from the second discharge port 33 of the image forming apparatus 100, a receiving path 225 for transporting the received sheets Sh, a pair of registration rollers 204 provided on the receiving path 225 for correcting the skew of the sheets Sh received at the first receiving port 201 and transporting them, a receiving flapper 203 for distributing the destination of the sheets Sh received at the first receiving port 201, a folding mechanism 210 for performing a folding process on the sheets Sh received at the first receiving port 201, and a folding mechanism 210 for transporting multiple sheets stacked on top of each other. The system includes a buffer path 226 and buffer roller pair 221 for holding a preceding sheet in a waiting position, a second receiving port 202 for receiving a sheet Sh discharged from the first discharge port 31 of the image forming apparatus 100, a through-transport path 228 and through-transport rollers 223 for transporting the sheet Sh received at the second receiving port 202 without going through the folding mechanism 210, a discharge roller pair 224 for discharging the sheet folded by the folding mechanism 210 and the sheet transported through the through-transport path 228, and a first tray 232 for loading the sheet discharged by the discharge roller pair 224.

[0052] The folding mechanism 210 of this embodiment includes a first roller 211, a second roller 212 for transporting the sheet Sh together with the first roller 211, a third roller 213 provided to the left of the second roller 212 for transporting and folding the sheet Sh together with the second roller 212, and a fourth roller 214 provided below the third roller 213 for transporting and folding the sheet Sh together with the third roller 213.

[0053] In this embodiment, the first roller 211 and the second roller 212 function as a transport roller pair 211, 212 that transport the sheet Sh received from the resist roller pair 204 in the left direction when viewed from the front of the device (in the horizontal component direction of the transport direction of the sheet Sh discharged from the second discharge port 33, the direction away from the second discharge port 33).

[0054] Furthermore, the second roller 212 and the third roller 213 function as a first folding roller pair for forming folds while conveying the sheet Sh, which has been transported by the first roller 211 and the second roller 212, downward in the vertical direction. In other words, the second roller 212 serves as both the transport roller pair 211, 212 and the folding roller pair 212, 213.

[0055] A first variable-speed roller pair 215 and a sensor SN3 are provided on the downstream side (left side when viewed from the front of the device) of the sheet conveying direction by the conveying roller pair 211, 212. When a fold is formed in the sheet Sh by the first folding roller pair 212, 213, the sheet Sh is transferred from the conveying roller pair 211, 212 to the first variable-speed roller pair 215. After the sensor SN3 detects the leading edge of the sheet Sh, the rotation speed of the first variable-speed roller pair 215 is reduced at a predetermined timing, causing a flex in the sheet Sh between the conveying roller pair 211, 212 and the first variable-speed roller pair 215. When the sheet Sh is flexed while the second roller 212 is rotating counterclockwise and the third roller 213 is rotating clockwise, the flexed sheet Sh is drawn into the nip point of the first folding roller pair 212, 213, and a fold is formed in the sheet Sh.

[0056] In this case, when the sheet Sh is conveyed downward by the first folding roller pair 212, 213, the first variable speed roller pair 215 may be rotated in the reverse direction to prevent the sheet Sh nipped by the first variable speed roller pair 215 from being pulled, or a torque limiter may be provided on the first variable speed roller pair 215 so that if the sheet Sh is pulled with a force exceeding a certain level, the first folding roller pair 212, 213 can pull the sheet Sh out of the first variable speed roller pair 215.

[0057] Furthermore, a second tray 233 is provided to the left of the first speed roller pair 215 when viewed from the front of the device, which supports the leading edge of the sheet Sh and serves as a first folded sleeve retraction area 230 for temporarily retracting the folded sleeve of the sheet Sh during the folding process.

[0058] Furthermore, a sheet guide 218 is provided between the transport roller pair 211, 212 and the first variable speed roller pair 215 to distribute the leading edge of the sheet Sh transported by the transport roller pair 211, 212 toward either the first variable speed roller pair 215 or the first folding roller pair 212, 213. When transporting the leading edge of the sheet Sh toward the first variable speed roller pair 215, the sheet guide 218 is positioned at the solid line position in Figure 3, and when transporting the leading edge of the sheet Sh toward the first folding roller pair 212, 213, the sheet guide 218 is positioned at the dashed line position in Figure 3, while the sheet Sh is transported by the transport roller pair 211, 212.

[0059] Furthermore, the third roller 213 and the fourth roller 214 function as a second folding roller pair to form folds while conveying the sheet Sh, which has been transported by the first folding roller pair 212, 213, in a leftward direction when viewed from the front of the device. In other words, the third roller 213 serves the dual function of both the first folding roller pair 212, 213 and the second folding roller pair 213, 214.

[0060] A second variable-speed roller pair 216 and a sensor SN4 are provided on the downstream side of the sheet transport direction by the first folding roller pair 212, 213 (to the lower right of the first folding roller pair 212, 213). When a fold is formed in the sheet Sh by the second folding roller pair 213, 214, the sheet Sh is transferred from the first folding roller pair 212, 213 to the second variable-speed roller pair 216. After the sensor SN4 detects the leading edge of the sheet Sh, the rotation speed of the second variable-speed roller pair 216 is reduced at a predetermined timing, causing a flex in the sheet Sh between the first folding roller pair 212, 213 and the second variable-speed roller pair 216. When the sheet Sh is flexed while the third roller 213 is rotating clockwise and the fourth roller 214 is rotating counterclockwise, the flexed sheet Sh is drawn into the nip point of the second folding roller pair 213, 214, and a fold is formed in the sheet Sh.

[0061] In this case, the second variable speed roller pair 216 may be rotated in the reverse direction to prevent the sheet Sh nipped by the second variable speed roller pair 216 from being pulled when the sheet Sh is conveyed to the left by the second folding roller pair 213, 214, or a torque limiter may be provided on the second variable speed roller pair 216 so that if the sheet Sh is pulled with a force exceeding a certain level, the sheet Sh can be pulled out from the second variable speed roller pair 216 by the second folding roller pair 213, 214.

[0062] Furthermore, below the second speed roller pair 216, there is a second folding sleeve retraction area 231 which temporarily retracts the folding sleeve of the sheet Sh during the folding process by the second folding roller pair 213, 214.

[0063] Furthermore, a flapper 220 is provided on the downstream side of the second variable speed roller pair 216 in the sheet transport direction. This flapper is movable to a first position (solid line in Figure 3) for guiding the leading edge of the sheet (the downstream end in the sheet transport direction by the second variable speed roller pair 216) to the second folded sleeve retraction area 231, and to a second position (dashed line in Figure 3) for guiding the sheet discharged from the first discharge port 31 of the image forming apparatus 100 to the through transport path 228.

[0064] The second folding sleeve retraction area 231 has a guide surface that guides the leading edge of the sheet Sh, which is being conveyed by the second variable-speed roller pair 216, to the left (away from the first discharge port 31). When folding long sheets with a length of 900 mm or more in the sheet conveying direction, the leading edge of the sheet is guided below the first tray 232 (part 231a). In other words, there are openings on the left side of the housing of the sheet folding device 200 and on the right side of the first tray 232, through which the sheet Sh can pass.

[0065] Furthermore, between the first folding roller pair 212, 213 and the second variable speed roller pair 216, there is a sheet guide 19 that can move to a first position (solid line in Figure 3) for guiding the leading edge of the sheet Sh conveyed by the first folding roller pair 212, 213 toward the second variable speed roller pair 216, and to a second position (dashed line in Figure 3, Figure 8(b)) for guiding the leading edge of the sheet toward the second folding roller pair 213, 214 so that it faces inward when performing the C-fold described later.

[0066] Here, the leftward direction mentioned above is not limited to the horizontal direction, but also includes the diagonal upward and diagonal downward directions, and it is sufficient that there is a leftward vector component in the direction of arrows LR (left-right direction). Similarly, the downward direction mentioned above is not limited to the vertical direction, but also includes the diagonal left and diagonal right directions, and it is sufficient that there is a downward vector component in the direction of arrow UD (up and down direction). The same applies to the rightward and upward directions. In other words, the vector component in the direction of arrow UD in the direction in which the first folding roller pair 212, 213 conveys the sheet Sh while folding it is the same as the vector component in the direction of arrow UD in the direction from the second discharge port 33 toward the first discharge port 31. Also, the vector component in the direction of arrows LR in the direction in which the second folding roller pair 213, 214 conveys the sheet Sh while folding it is the same as the vector component in the direction of arrows LR in the direction from the second discharge port 33 toward the folding mechanism 210.

[0067] The folding mechanism 210 described above is configured to allow the Z-folded sheet to be discharged face down (see sheet Sh in the first tray 232 in Figure 3). It first forms a fold by conveying the sheet Sh received by the conveyor roller pair 211, 212 downwards with the first folding roller pair 212, 213, and then conveying the sheet Sh to the left with the second folding roller pair 213, 214, which has a nip portion vertically below the nip portion of the first folding roller pair 212, 213, to form a second fold on the rear end side of the sheet beyond the first fold.

[0068] In other words, the nip portions of the second folding roller pair 213, 214 are positioned vertically below the nip portions of the transport roller pair 211, 212, and the sheet Sh is folded as it moves from top to bottom within the folding mechanism 210. Since the sheet folding device 200 of this embodiment is positioned in the internal space 50 of the image forming apparatus 100, which has vertical constraints, it is desirable that the receiving opening for the sheet Sh in the sheet folding device 200 be positioned as high up in the device as possible.

[0069] If, in the conventional manner, the sheet Sh is to be transferred from the first discharge port 31 of the image forming apparatus 100 to the first receiving port 201 in such a sheet folding device 200, an upward path is required to connect the first discharge port 31 to the first receiving port 201, which increases the width size of the sheet folding device 200 (size in the direction of arrows LR).

[0070] Therefore, in this embodiment, the sheet Sh is transferred from the second discharge port 33, which is located vertically above the first discharge port 31 of the image forming apparatus 100, to the first receiving port 201 of the sheet folding apparatus 200. In the vertical direction, the second discharge port 33, the nip portion of the resist roller pair 204, and the nip portions of the conveyor roller pair 211, 212 are positioned above the first discharge port 31. In other words, the second discharge port 33, the nip portion of the resist roller pair 204, and the nip portions of the conveyor roller pair 211, 212 are at approximately the same height in the vertical direction. As a result, an upward path connecting the first discharge port 31 to the first receiving port 201 is unnecessary, and the width size of the sheet folding apparatus 200 is made more compact. It goes without saying that when conveying the sheet received from the second discharge port 33 toward the nip portion of the register roller pair 4 or the conveyor roller pair 211, 212, there may be some upward or downward paths (the width is more compact than when receiving the sheet Sh from the first discharge port 31).

[0071] Furthermore, the nip portion of the discharge roller pair 224 that discharges the folded sheet Sh is positioned vertically below the second discharge port 33 and at approximately the same height as the first discharge port 31. This allows the in-body finisher 300 (sheet binding device) to be installed alongside the sheet folding device 200 in the body space 50, as shown in Figure 11, to receive the sheet Sh discharged from the discharge roller pair 224 of the sheet folding device 200 at the receiving port 301 of the in-body finisher 300. The in-body finisher 300 can also be attached to the image forming apparatus 100 without the sheet folding device 200, in which case the receiving port 301 of the in-body finisher 300 is configured to be at a height that can receive the sheet Sh discharged from the first discharge port 31 of the image forming apparatus 100.

[0072] In other words, if we define the height position of the first discharge port 31 as the first height position and the height position of the second discharge port 33 as the second height position in the vertical direction, then the first receiving port 201 of the sheet folding device 200, the nip portion of the register roller pair 204, and the nip portion of the conveying roller pair 211, 212 are positioned at a height closer to the second discharge port 33 than the height position midway between the first and second height positions. The second receiving port 202 of the sheet folding device 200, the through conveying path 228, the discharge roller pair 224, and the receiving port 301 of the in-body finisher 300 are positioned at a height closer to the first discharge port 31 than the height position midway between the first and second height positions.

[0073] In this configuration, when folding is performed on a sheet, the sheet Sh is passed from the second discharge port 33 of the image forming apparatus 100 to the first receiving port 201 of the sheet folding apparatus 200, and the sheet Sh is folded while being lowered, and then passed from the discharge roller pair 224 below to the receiving port 301 of the in-body finisher 300. This eliminates unnecessary vertical transport of the sheet Sh, resulting in a compact image forming system 1000 in the direction of arrows LR.

[0074] Conventionally, sheets discharged from the first discharge port 31 of the image forming apparatus 100 were handed over to the sheet folding device, requiring an upward pass. Due to the large width, it was not possible to install the sheet folding device and sheet binding device side by side in the internal space 50 of the machine body. The mainstream image forming system was one in which the sheet folding device was installed in the internal space 50 and an external sheet binding device (external finisher) was installed to the left of the image forming apparatus 100. However, because the sheet folding device 200 of this embodiment has a compact width, it is possible to provide a compact image forming system 1000 in which the internal folding device 200 and internal finisher 300 are installed side by side in the internal space 50 of the machine body. Therefore, conventionally, users who wanted to perform both folding and binding on sheets only had the option of an external finisher, but with the image forming system 1000 of this embodiment, an internal finisher can also be selected.

[0075] Here, the internal finisher 300 of this embodiment will be described. The internal finisher 300 receives the sheet Sh at the receiving port 301, transports the sheet Sh with the transport roller pair 302 and 303, drops the sheet Sh transported from the transport roller pair 303 toward the processing tray 304 with the rear end dropping member 305, and uses the scraping paddle 306 and knurled belt 307 to abut the rear end of the sheet Sh toward the rear end abutting member 308, and a pair of alignment plates 309 align the sheet in the width direction. By repeating this operation, a sheet bundle is formed on the processing tray 304, and the sheet bundle is stapled by a stapler 310 or the like. The stapled sheet bundle is discharged to the loading tray 312 by the discharge roller pair 311a and 311b, and its upper surface is pressed down by the sheet pressing member 313.

[0076] Such an in-body finisher 300 can perform binding on both sheets that are discharged from the first discharge port 31 of the image forming apparatus 100 and have not been folded, and sheets that have been discharged from the second discharge port 33 of the image forming apparatus 100 and have been folded. Furthermore, if binding is not performed, the sheets can be transferred from the transport roller pair 303 to the discharge roller pair 311a, 311b and discharged directly to the loading tray 312, or the sheets can be shifted in the sheet width direction using the alignment plate 309 before being discharged to the loading tray 312.

[0077] Furthermore, when the sheet folding device 200 and the in-body finisher 300 are installed, the first tray 232 and the second tray 233 of the sheet folding device 200 are removed and installed separately. When discharging a long sheet of 500 mm or more in length, the long sheet is passed from the second discharge port 33 of the image forming apparatus 100 to the first receiving port 201 of the sheet folding device 200, and discharged to the upper surface of the device housing of the in-body finisher 300 by the first variable-speed roller pair 215. The upper surface of the device housing of the in-body finisher 300 also functions as a folding sleeve retraction area 231 during the folding process.

[0078] Furthermore, the internal finisher 300 is supported by a rail (not shown) and is configured to be able to move away from the sheet folding device 200 to the left in order to remove jammed sheets when jams occur. In addition, if the sheet that has been retracted into the second folding sleeve retraction area 231 described above is a long sheet of 900 mm or more, it is configured so that the sheet can be inserted inside the rail.

[0079] <Control Unit> Next, the control configuration of the image forming system 1000 will be explained with reference to the block diagram in Figure 12.

[0080] First, the image forming apparatus 100 includes a main unit control unit 60, an operation unit 11, a paper feeding control unit, a transport control unit, an image processing unit, a reading processing unit, and a communication unit 61. The main unit control unit 60 includes a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory).

[0081] The operation unit 11 is connected to the main unit control unit 60 and is, for example, an operation panel provided on the image forming apparatus 100, where the operator operates the apparatus and makes various settings. The paper feed control unit and the transport control unit control the drive mechanisms of various transport rollers that transport sheets and switching members that switch transport paths in the image forming apparatus 100. The image processing unit controls each mechanism of the image forming unit 1. The reading control unit controls each mechanism of the reading unit 40. The communication unit 61 connects the main unit control unit 60 to external devices 400 such as a personal computer and the folding machine control unit 250 via the communication unit 251 of the sheet folding device 200, enabling communication between the main unit control unit 60 and external devices 400 such as a personal computer or the folding machine control unit 250.

[0082] The sheet folding device (internal folding machine) 200 includes a folding machine control unit 250, a communication unit 251 that communicates with the image forming apparatus 100, various sensors, and various drive mechanisms. The sheet folding device 200 of this embodiment includes an inlet sensor SN1 for detecting a sheet Sh received from a first inlet 201, a buffer path sensor SN2 for detecting a sheet Sh guided to a buffer path 226, a first folding sensor SN3 for detecting the leading edge of a sheet Sh being conveyed by a first variable-speed roller pair 215, a second folding sensor SN4 for detecting the leading edge of a sheet Sh being conveyed by a second variable-speed roller pair 216, and a discharge sensor SN5 for detecting the trailing edge of a sheet Sh being discharged by a discharge roller pair 224. Based on signals from these various sensors, the folding machine control unit 250 controls the various drive mechanisms.

[0083] The sheet folding device 200 of this embodiment includes a flapper drive motor MT1 that drives the receiving flapper 203, flapper 220, and flapper 222; a register roller drive motor MT2 that drives the register roller pair 204; a sheet guide moving motor MT3 that drives the sheet guides 218 and 219; a folding roller drive motor MT4 that drives the first roller 211, second roller 212, third roller 213, fourth roller 214, additional folding roller pair 217, and discharge roller pair 224; a first variable speed roller drive motor MT5 that drives the first variable speed roller pair 215; and a second variable speed roller drive motor MT6 that drives the second variable speed roller pair 216 and buffer roller pair 221.

[0084] The internal finisher 300 of this embodiment includes a finisher control unit 320, a communication unit 321 that communicates with the communication unit 251 of the sheet folding device 200, various sensors, and various drive mechanisms. The internal finisher 300 of this embodiment includes an inlet sensor SN11 for detecting a sheet Sh received from the receiving inlet 301, a pre-processing sensor SN12 for detecting the rear end of the sheet Sh conveyed by the transport roller pair 303, a lifting HP sensor SN13 for detecting the home position when the rear end drop member 305, scraping paddle 306, and upper discharge roller 311b move up and down, a alignment plate HP sensor SN14 for detecting the home position of the alignment plate 309, an STP movement HP sensor SN15 for detecting the home position when the stapler 310 moves in the sheet width direction, a paper surface detection sensor SN16 for detecting the upper surface of a sheet loaded on the loading tray 312, and a loading tray lower limit sensor SN17 for detecting the lower limit position when the loading tray 312 moves up and down. Based on signals from these various sensors, the finisher control unit 320 controls various drive mechanisms.

[0085] The internal finisher 300 of this embodiment includes a transport roller drive motor MT11 that drives the transport roller pair 302, 303 and the knurled belt 307, a lifting motor MT12 that raises and lowers the rear end drop member 305, the scraping paddle 306 and the upper discharge roller 311b, a return drive motor that drives the scraping paddle 306 in the sheet scraping direction, a discharge roller drive motor MT14 that drives the discharge roller 311a, a matching plate drive motor MT15 that drives the matching plate 309, an STP moving motor MT16 that moves the stapler 310 in the sheet width direction, an STP drive motor MT17 that performs the clinching operation of the stapler 310, and a loading tray lifting drive motor MT18 that raises and lowers the loading tray 312.

[0086] The main unit control unit 60 of the image forming system 1000 in this embodiment operates the sheet folding device 200 and the in-cylinder finisher 300 according to the sheet processing mode settings input from the operation unit 11 and external equipment 400. The processing modes that can be input from the operation unit 11 and external equipment 400 include "straight discharge", "V-fold (double fold)", "C-fold (inner tri-fold)", "Z-fold (outer tri-fold)", "quadruple fold" (setting for overlapping folds of multiple sheets for each fold), "binding", "Z-fold + binding", and "shift discharge".

[0087] The operation of the sheet folding device 200 will now be described. Each mechanism is controlled and operated by the main unit control unit 60 and the folding machine control unit 250. First, the register operation of the sheet Sh received from the second discharge port 33 of the image forming apparatus 100 will be described using Figures 4(a) to 4(c). The sheet Sh on which the image has been formed passes through the second discharge path 29 and its leading edge is discharged from the second discharge port 33 by the second discharge roller pair 32. The sheet folding device 200 receives the sheet Sh at the first receiving port 201 with the receiving flapper 203 positioned at the receiving position shown in Figure 4(a) and the rotation of the register roller pair 204 stopped. At this time, the leading edge of the sheet Sh is detected by the inlet sensor SN1.

[0088] When the inlet sensor SN1 detects the leading edge of the sheet Sh, the receiving flapper 203 moves to the loop-forming position shown in Figure 4(b), and the rotation of the register roller pair 204 is stopped while the second discharge roller pair 32 is continuously driven, causing the leading edge of the sheet Sh to abut against the register roller pair 204 and correcting the skew of the sheet Sh. Subsequently, a predetermined time after the inlet sensor SN1 detects the leading edge of the sheet Sh, the register roller pair 204 is rotated as shown in Figure 4(c) to transport the sheet Sh toward the folding mechanism 210.

[0089] Next, when performing double-sided printing on a sheet Sh using the image forming apparatus 100, the operation of reversing the front and back sides of the sheet Sh will be explained using Figures 5(a) to (c). First, the receiving flapper 203 of the sheet folding apparatus 200 is moved to the reversal position shown in Figure 5(a). In this state, the leading edge of the sheet Sh is transported above the receiving flapper 203 by the second discharge roller pair 32. Since there is no member to nip the sheet Sh above the receiving flapper 203, the sheet Sh is nipped and transported only by the second discharge roller pair 32.

[0090] The sheet Sh is conveyed by the second discharge roller pair 32, and as shown in Figure 5(b), when the rear end of the sheet passes the branching point of the second discharge path 29 and the reversal path 34 (when the rear end of the sheet is detected by a sensor not shown), the flapper 35 shown in Figure 1 is moved counterclockwise to reverse the second discharge roller pair 32. As a result, the rear end of the sheet Sh is guided over the flapper 35 to the reversal path 34 (Figure 5(c)).

[0091] Next, in order to perform the folding process with multiple sheets stacked on top of each other, the operation of stacking the sheets will be explained using Figures 6(a) to (d). First, with the receiving flapper 203 of the sheet folding device 200 in the receiving position shown in Figure 6(a), the first sheet Sh1 is discharged from the second discharge port 33 by the second discharge roller pair 32, and the sheet Sh1 is received by the first receiving section 201 of the sheet folding device 200. At this time, the register operation described in Figures 4(a) to (c) is performed. After that, once the rear end of the sheet has passed the inlet sensor SN1, the receiving flapper 203 is moved to the inversion position shown in Figure 6(b), and the register roller pair 204 is reversed to transfer the sheet Sh1 to the buffer roller pair 221 of the buffer path 226.

[0092] The sheet Sh1, which has been passed to the buffer roller pair 221, is transported until its leading edge is detected by the buffer sensor SN2. At this time, the flapper 222 shown in Figure 3 is in the position indicated by the solid line, and the rear end of the sheet Sh1 is guided to the second folding sleeve retraction area 231. After that, the receiving flapper 203 moves to the receiving position shown in Figure 6(c) to receive the second sheet Sh2. Once the sheet Sh2 is detected by the inlet sensor SN1, the buffer roller pair 221 is driven to transport the sheets towards the register roller pair 204 so that the leading edges of sheets Sh1 and Sh2 align.

[0093] Subsequently, the receiving flapper 203 is moved to the loop formation position shown in Figure 6(d), and sheets Sh1 and Sh2 are brought into contact with the stopped register roller pair 204 to form loops while correcting the skew. After a predetermined time has elapsed, the register roller pair 204 is rotated to transport the two sheets together toward the folding mechanism 210. In this embodiment, three sheets can be folded together. When three sheets are folded together, the first sheet Sh1 and the second sheet Sh2 are guided to the buffer path 226, and after the third sheet is added and the register operation is performed, they are transported toward the folding mechanism 210. The sheet folding device 200 in this embodiment can fold sheets with a basis weight of 52 to 128 gsm, but when performing a C-fold with three sheets, the upper limit of the basis weight is, for example, 105 gsm per sheet.

[0094] Next, the folding operation will be explained using Figures 7(a) to 9(b). The following explanation describes the folding of a single sheet, but the operation of the folding mechanism 210 is the same for overlapping folds, so the explanation will be omitted. Furthermore, the operation after the sheet Sh, which has undergone the register operation shown in Figures 4(a) to (c), is received by the folding mechanism 210 will be explained.

[0095] The Z-fold operation will be explained using Figures 7(a) to 7(c). First, the sheet Sh is transported from the transport roller pair 211, 212 toward the first variable-speed roller pair 215. When the sheet Sh transported by the first variable-speed roller pair 215 is detected by the first folding sensor SN3, the first variable-speed roller pair 215 is decelerated after a predetermined time to form a loop with the transport roller pair 211, 21 (Figure 7(a)). In this case, since it is a Z-fold, the loop is formed so that the first fold is formed at a position 1 / 4 of the way from the leading edge of the sheet Sh to the total length of the sheet, and the first folding roller pair 212, 213 performs the first folding process on the sheet Sh.

[0096] Subsequently, the sheet Sh is transported to the second variable speed roller pair 216 with the first fold as the leading edge. After the second folding sensor SN4 detects the leading edge of the sheet Sh (the first fold), the second variable speed roller pair 216 is decelerated after a predetermined time to form a loop with the first folding roller pair 212 and 213 (Figure 7(b)). At this time, the loop is formed such that the second fold is formed at a position half the length of the sheet from the leading edge of the sheet Sh (towards the rear end of the sheet from the first fold), and the second folding roller pair 213 and 214 perform the second folding process on the sheet Sh. At this time, the flapper 222 guides the leading edge of the sheet Sh toward the second folding sleeve retraction area 213 at the position shown in the figure.

[0097] As a result, as shown in Figure 7(c), a face-down Z-fold can be performed where the leading edge of the sheet Sh and the first fold are located on the underside of the sheet Sh. After passing through the nip portion of the second folding roller pair 213, 214, the sheet Sh is subjected to an additional folding process by the additional folding roller pair 217 and then conveyed toward the discharge roller pair 224.

[0098] Next, the C-fold operation will be explained using Figures 8(a) to 8(c). First, the sheet Sh is transported from the transport roller pair 211, 212 toward the first variable-speed roller pair 215. When the sheet Sh transported by the first variable-speed roller pair 215 is detected by the first folding sensor SN3, the first variable-speed roller pair 215 is decelerated after a predetermined time to form a loop with the transport roller pair 211, 21 (Figure 8(a)). In this case, since it is a C-fold, the loop is formed so that the first fold is formed at a position 1 / 3 of the total length of the sheet from the rear end of the sheet Sh, and the first folding roller pair 212, 213 performs the first folding process on the sheet Sh.

[0099] Next, with the first fold as the leading edge, the sheet Sh is passed from the first folding roller pair 212, 213 to the second variable speed roller pair 216. When the second folding sensor SN4 detects the first fold of the sheet Sh, the sheet guide 219 moves to the position shown in Figure 8(b) while decelerating the second variable speed roller pair 216, forming a loop with the first folding roller pair 212, 213. At this time, the sheet guide 219 guides the rear end of the sheet so that it is guided to the nip portion of the second folding roller pair 213, 214.

[0100] Then, a loop is formed so that the second fold is formed at a position 1 / 3 of the way from the leading edge of the sheet Sh (closer to the leading edge than the first fold), and the second folding process is performed on the sheet Sh by the second folding roller pair 213, 214. At this time, the flapper 222 guides the first fold of the sheet Sh toward the second folding sleeve retraction area 213 at the position shown in the figure.

[0101] Subsequently, the sheet Sh, having passed through the nip portion of the second folding roller pair 213, 214, is subjected to further folding by the additional folding roller pair 217 before being conveyed toward the discharge roller pair 224 (Figure 8(c)).

[0102] Next, the V-folding operation will be explained using Figures 9(a) and 9(b). First, the sheet guide 218 is moved to the position shown in Figure 9(a) and the leading edge of the sheet Sh is transported so that it is guided from the transport roller pair 211, 212 toward the first folding roller pair 212, 213. That is, the sheet Sh is transported toward the second variable speed roller pair 216 without being folded by the first folding roller pair 212, 213. When the leading edge of the sheet Sh transported by the second variable speed roller pair 216 is detected by the second folding sensor SN4, the second variable speed roller pair 216 is decelerated after a predetermined time to form a loop with the first folding roller pair 212, 213. At this time, the flapper 222 guides the leading edge of the sheet Sh toward the second folding sleeve retraction area 213 at the position shown.

[0103] In this case, since it is a V-fold, a loop is formed so that the fold is formed at a position halfway along the total length of the sheet from the leading edge of the sheet Sh, and the sheet Sh is folded by the second folding roller pair 213 and 214. The sheet Sh that has been folded by the second folding roller pair 213 and 214 is then further folded by the additional folding roller pair 217 and then conveyed toward the discharge roller pair 224.

[0104] Alternatively, the V-fold may be formed by creating a crease with the first folding roller pair 212, 213, and then guided by the sheet guide 219 to the second folding roller pair 213, 214 with the crease as the leading edge, without performing any folding on the second folding roller pair 213, 214.

[0105] Figure 10 illustrates a through-convey operation in which a sheet Sh is discharged without being folded. The image forming system 1000 of this embodiment is equipped with a sheet folding device 200, but not all sheets are folded. If the sheets are not folded, they can be conveyed using sheet guides 218 and 219, passing from the conveyor roller pair 211 and 212 to the first folding roller pair 212 and 213 and the second folding roller pair 213 and 214, and then toward the discharge roller pair 224. However, if the sheet is made of cardboard with a basis weight of 300 gsm or more, conveying it with this curvature may damage the sheet.

[0106] Therefore, in this embodiment, the flappers 220 and 222 are moved to the position shown in Figure 10, and the sheet Sh discharged from the first discharge port 31 of the image forming apparatus 100 is received from the second receiving port 202 of the sheet folding apparatus 200 and guided to the through-conveyor path 228. The sheet Sh is then nipped and conveyed by the lower roller (drive roller) of the second variable speed roller pair 216 located on the through-conveyor path 228 and the through-conveyor roller 223 located opposite it, and then handed over to the discharge roller pair 224.

[0107] The through-conveyor path 228 is a conveyor path that extends vertically downward from the folding mechanism 210 in the direction of arrows LR, and connects the first discharge port 31 to the discharge roller pair 224 with a gentle curve, so it can also convey cardboard with a basis weight of 300 gsm or more.

[0108] As described above, the sheets Sh that have been folded or conveyed through each operation are discharged to the first tray 232 by the discharge roller pair 224, or, if the internal finisher 300 is connected, are handed over to the receiving port 301 of the internal finisher 300.

[0109] <Modified Version> In the embodiment described above, when performing double-sided printing on a sheet Sh with the image forming apparatus 100, the leading edge of the sheet Sh is discharged from the second discharge port 33 and the rear end of the sheet Sh is guided to the reversal path 34. However, as shown in Figure 13, the reversal operation may be performed using the first discharge port 31. In the modified version shown in Figure 13, a flapper 28 is provided that distributes the sheet Sh from the transport path 26 to the first discharge path 27 and the relay path 29a that leads to the second discharge path 29, a flapper 35a that guides the rear end of the sheet from the first discharge path 27 to the reversal path 34 using the first discharge roller pair 30, and a flapper 35b that guides the sheet Sh, which has been transported to the relay path 29a on the reversal path 34, to the second discharge path 29.

[0110] When performing the reversal operation of the sheet Sh with this configuration, the flapper 222 is moved to the position shown in Figure 13, and the sheet Sh is discharged from the first discharge port 31 by the first discharge roller pair 30, guiding the leading edge of the sheet Sh toward the second folding sleeve retraction area 231. As a result, the sheet Sh is nipped only by the first discharge roller pair 30, and once the rear end of the sheet Sh passes the branching point between the first discharge path 27 and the reversal path 34, the first discharge roller pair 30 is reversed, and the flappers 35a and 35b are moved to the position shown in Figure 13, guiding the sheet Sh from the rear end toward the reversal path 34.

[0111] In the embodiment described above, the second roller 212 serves as both the transport roller pair 211, 212 and the first folding roller pair 212, 213, and the third roller 213 serves as both the first folding roller pair 212, 213 and the second folding roller pair 213, 214. However, the rollers may not be shared and each may have a separate roller pair, or only one of them may be shared.

[0112] Furthermore, in the above-described embodiment, a configuration was shown in which the sheet is discharged from the first discharge port 31 using the first discharge roller pair 30 and the sheet is discharged from the second discharge port 33 using the second discharge roller pair 32. However, a configuration may also be provided in which a single discharge roller pair is used to distribute the sheet to the first discharge port 31 and the second discharge port 33 using a flapper. Alternatively, the sheet may be discharged from the second discharge port 33 using the first discharge roller pair 30 and the sheet may be discharged from the first discharge port 31 using the second discharge roller pair 32.

[0113] Although the present invention has been described with reference to exemplary embodiments, the present invention is not limited to the exemplary embodiments disclosed. The scope of the following claims is given in the broadest sense to encompass all variations, equivalent structures and functions.

[0114] This application claims priority based on Japanese Patent Application No. 2025-050818, filed on 25 March 2025, and all of its contents are incorporated herein by reference.

Claims

1. An image forming system comprising an image forming apparatus for forming an image on a sheet and a sheet folding apparatus for folding a sheet received from the image forming apparatus, wherein the image forming apparatus comprises: an image forming unit for forming an image on a sheet; a reading unit positioned above the image forming unit for reading an image from a document; a first discharge port from which the sheet on which the image has been formed by the image forming unit is discharged toward a space inside the cylinder formed between the image forming unit and the reading unit; a second discharge port positioned vertically above the first discharge port from which the sheet on which the image has been formed is discharged toward the space inside the cylinder, wherein the sheet folding apparatus is provided in the space inside the cylinder, and the sheet folding apparatus comprises a receiving unit positioned vertically above the first discharge port for receiving a sheet discharged from the second discharge port, An image forming system comprising: a pair of first folding rollers that convey a sheet received in the receiving section vertically downward while making a first fold; a pair of second folding rollers that convey the sheet folded by the pair of first folding rollers in a direction toward the receiving section from the second discharge port while making a second fold on the rear end side of the sheet beyond the first fold, and a folding mechanism capable of performing a Z-fold on the sheet so that the first fold is on the lower surface side of the sheet; and a conveying mechanism that conveys the sheet received from the first discharge port without passing through the folding mechanism.

2. An image forming system comprising an image forming apparatus for forming an image on a sheet and a sheet folding apparatus for folding a sheet received from the image forming apparatus, wherein the image forming apparatus comprises: an image forming unit for forming an image on a sheet; a sheet reversing unit for receiving the sheet on which the image has been formed by the image forming unit from the rear end of the sheet and transporting the sheet back to the image forming unit; a reading unit positioned above the image forming unit for reading an image from a document; a first discharge port from which the leading edge of the sheet is discharged toward a space inside the cylinder formed between the image forming unit and the reading unit until the rear end of the sheet on which the image has been formed by the image forming unit can be received by the sheet reversing unit; and a second discharge port positioned vertically above the first discharge port from which the sheet on which the image has been formed is discharged toward the space inside the cylinder, wherein the sheet folding apparatus is provided in the space inside the cylinder, and the sheet folding apparatus comprises a receiving unit positioned vertically above the first discharge port for receiving the sheet discharged from the second discharge port. An image forming system comprising: a pair of first folding rollers that convey a sheet received in the receiving section vertically downward while making a first fold; and a pair of second folding rollers that convey the sheet folded by the pair of first folding rollers in a direction toward the receiving section from the second discharge port while making a second fold on the rear end side of the sheet beyond the first fold, and a folding mechanism capable of performing a Z-fold on the sheet so that the first fold is on the lower surface side of the sheet.

3. The image forming system according to claim 1 or 2, wherein the receiving section is a pair of conveying rollers that receive the sheet discharged from the second discharge port, and the nip portion of the pair of conveying rollers is positioned vertically above an intermediate height position connecting the first discharge port and the second discharge port.

4. The image forming apparatus comprises a sheet reversing unit that receives the sheet from the rear end of the sheet and transports the sheet back to the image forming unit after an image has been formed by the image forming unit and the leading edge of the sheet has been discharged from the second discharge port, and the sheet folding apparatus comprises a sheet guide unit that guides the leading edge of the sheet transported from the second discharge port, and the sheet guide unit guides the sheet toward the folding mechanism when performing a folding process on the sheet transported from the second discharge port, and guides the leading edge of the sheet above the folding mechanism when transporting the sheet to the sheet reversing unit, characterized in that the image forming system according to claim 1.

Images