Image forming apparatus

Abstract

The sheet is cut in a state in which the entire sheet passes through the nip. An image forming apparatus (1) includes an apparatus main body (2), an image forming section, a fixing device (6), and a cutter (7). The image forming section forms an image on a sheet. The fixing device (6) has a heating rotating body (61) and a pressing rotating body (62) forming a nip (NP) between the heating rotating body (61) and the pressing rotating body (62), and fixes an image to a sheet (S). The cutter (7) is disposed on the downstream side of the fixing device (6) in the conveying direction of the sheet (S), and is capable of cutting the sheet (S). The cutter (7) is capable of cutting a sheet (S) to be cut at a center position (PP) in a conveyance direction of the sheet (S). The distance D1 at which the sheet (S) is conveyed from the nip (NP) to the cutter (7) is greater than half of the dimension LS of the sheet (S) in the conveying direction D1 > LS / 2.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus including a cutter. Background Art

[0002] Conventionally, there is known an image forming apparatus equipped with a cutter (Patent Document 1). This image forming apparatus can cut a single sheet into two sheets when it is determined that the sheet needs to be cut.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-160228

[0006] Technical problem to be solved by the invention

[0007] However, in an image forming device that heats and pressurizes a toner image that has formed an image in a clamping portion of a fixing device to fix it, if the sheet is stopped from being transported and cut without the entire sheet passing through the clamping portion, there is a problem that the sheet is excessively heated and pressurized in the clamping portion. Summary of the invention

[0008] Therefore, an object of the present invention is to cut a sheet material while the entire sheet material has passed through a nip portion.

[0009] An image forming device for achieving the above-mentioned purpose comprises a device body, an image forming unit, a fixing device and a cutter. The image forming unit forms an image on a sheet. The fixing device comprises a heating rotating body and a pressurizing rotating body forming a clamping portion with the heating rotating body, and the fixing device fixes the image on the sheet. The cutter is arranged on the downstream side of the sheet conveying direction of the fixing device and is capable of cutting the sheet. The cutter is capable of cutting the sheet at the center position in the conveying direction of the sheet. The distance that the sheet is conveyed from the clamping portion to the cutter is greater than half of the dimension of the sheet to be cut in the conveying direction.

[0010] According to such a structure, the sheet can be cut while the entire sheet has passed through the nip portion. Therefore, even if the sheet is cut while the conveyance of the sheet is stopped, it is possible to prevent the sheet from being excessively heated or pressurized in the nip portion.

[0011] In addition, the following structure can also be set: the cutter can at least cut the A4 size sheet at the center position in the conveying direction of the sheet, and in the conveying direction, the distance the sheet is conveyed from the clamping part to the cutter is greater than half of the size of the A4 size sheet in the conveying direction.

[0012] According to this, the A4-size sheet can be cut while the entire sheet has passed through the nip portion. Therefore, even if the sheet is cut while the conveyance of the sheet is stopped, it is possible to prevent the sheet from being excessively heated or pressurized in the nip portion.

[0013] In addition, the following structure can also be set: the cutter can at least cut the letter-sized sheet at the center position in the conveying direction of the sheet, and in the conveying direction, the distance the sheet is conveyed from the clamping part to the cutter is greater than half the size of the letter-sized sheet in the conveying direction.

[0014] Thus, the letter-sized sheet can be cut while the entire sheet has passed through the nip portion. Therefore, even if the sheet is cut while the conveyance of the sheet is stopped, it is possible to prevent the sheet from being excessively heated or pressurized in the nip portion.

[0015] In addition, the structure may be as follows, that is, it further comprises: a conveying roller, which is located on the upstream side of the sheet conveying direction relative to the cutter, can rotate axially, and conveys the sheet toward the cutter; and a discharge roller, which is located on the downstream side of the sheet conveying direction relative to the cutter, can rotate axially, and discharges the sheet to the outside of the device body, and the axial dimensions of the conveying roller and the discharge roller are larger than half the width of the maximum width of the sheet that can be conveyed by the image forming device.

[0016] According to this, when the sheet is cut, the conveying roller or the discharge roller holds the sheet in a wide area in the width direction of the sheet, thereby suppressing positional deviation of the sheet when cutting.

[0017] Alternatively, a configuration may be adopted in which the dimension in the axial direction of at least one of the transport roller and the discharge roller is larger than the width of the maximum width of a sheet that can be transported by the image forming apparatus.

[0018] According to this, when the sheet is cut, the conveying roller or the discharge roller holds the sheet in a wide area in the width direction of the sheet, thereby suppressing positional deviation of the sheet when cutting.

[0019] In addition, the structure may be as follows, that is, it further comprises: a conveying roller, which is located on the upstream side of the cutter in the conveying direction of the sheet and conveys the sheet toward the cutter; a re-conveying path, which guides the sheet that has passed the fixing device toward the image forming unit again; and a control unit, which uses the cutter to cut a sheet into two sheets, and the control unit can convey the sheet on the upstream side of the conveying direction of the cut sheet to the re-conveying path by reversing the conveying roller.

[0020] According to this, the cut sheet can be re-conveyed to form an image.

[0021] Furthermore, the structure may be such that a control unit is further provided, and when receiving a command to cut the sheet, the control unit cuts the sheet while stopping the conveyance of the sheet.

[0022] According to this, the sheet can be cut straightly in the axial direction.

[0023] In addition, the structure may be as follows, that is, comprising: a first conveying path, which guides the sheet after being fixed by the fixing device to the outside of the device body; a second conveying path, which is a conveying path different from the first conveying path and guides the sheet after being fixed by the fixing device to the outside of the device body; and a control unit, which conveys the sheet to the first conveying path without cutting the sheet by a cutter, and conveys the sheet to the second conveying path when the sheet is cut by a cutter.

[0024] In addition, the following structure can also be set, that is, it also includes: a first discharge outlet, which discharges the sheet from the first conveying path to the outside of the device body; and a second discharge outlet, which discharges the sheet from the second conveying path to the outside of the device body, and the first discharge outlet is located closer to the fixing device than the second discharge outlet.

[0025] According to this, the second discharge roller is preferably separated from the fixing device by a predetermined distance in order to discharge the sheet cut by the cutter. Therefore, by locating the first discharge roller closer to the fixing device than the second discharge roller, the device main body can be miniaturized.

[0026] In addition, the following structure can also be set: a control unit is provided, and when the control unit receives an instruction to cut the sheet, when the dimension in the conveying direction from the predetermined cutting position of the sheet to the rear end position of the sheet is shorter than the conveying distance of the sheet from the clamping part to the cutter, the sheet is cut by the cutter.

[0027] According to this, the sheet can be cut while the entire sheet has passed through the nip portion. Therefore, even if the sheet is cut while the conveyance of the sheet is stopped, it is possible to prevent the sheet from being excessively heated or pressurized in the nip portion.

[0028] Furthermore, an input unit capable of inputting a cutting position of the sheet may be provided, and the control unit may cut the sheet based on a command input to the input unit.

[0029] In addition, the structure may be as follows, that is, it further comprises: a conveying roller, which is located on the upstream side of the cutter in the conveying direction of the sheet and conveys the sheet to the cutter; and a control unit, and when the sheet is conveyed to the cutter, the control unit starts rotating the conveying roller after the front end of the sheet in the conveying direction contacts the conveying roller.

[0030] According to this, even when the sheet is conveyed while being inclined with respect to the conveying direction, the oblique travel can be suppressed by making the sheet contact with the conveying roller.

[0031] In addition, the structure may be as follows, that is, it further comprises: a conveying roller, which is located on the upstream side of the cutter in the conveying direction of the sheet and conveys the sheet toward the cutter; and a discharge roller, which is located on the downstream side of the cutter in the conveying direction of the sheet and discharges the sheet to the outside of the device body, and the conveying speed of the discharge roller is greater than the conveying speed of the conveying roller.

[0032] This can suppress slack of the sheet between the conveying roller and the discharge roller.

[0033] In addition, it is possible to suppress interference between the cut sheets.

[0034] Effects of the Invention

[0035] According to the present invention, the sheet can be cut in a state where the entire sheet has passed through the nip portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a diagram showing the structure of an image forming apparatus according to an embodiment.

[0037] Figure 2 It is a three-dimensional diagram of the cutter.

[0038] Figure 3 yes Figure 2 A partial enlarged view of .

[0039] Figure 4 It is a figure which shows the conveyance distance from a clamping part to a cutter.

[0040] Figure 5 This is a diagram comparing the axial dimensions of the sheet, the folding roller, and the second discharge roller.

[0041] Figure 6 This is a diagram showing the electrical connection between the control unit and each motor, damper, and each sensor.

[0042] Figure 7 This is a flowchart showing an example of processing executed by the control unit after receiving a job.

[0043] Figure 8 This is a timing chart for explaining the timing of sheet feeding, sheet conveyance, and cutting controlled by the control unit.

[0044] Fig. 9 This is a diagram showing an image forming apparatus after a cut sheet is ejected.

[0045] Fig.10 This is a diagram showing an image forming apparatus in a form including a second discharge tray.

[0046] Fig.11 This is a diagram showing an image forming apparatus in a form including a scanner unit.

[0047] Fig.12 FIG. 1 is a diagram showing a sheet cut into two by a cutter (a), and FIG. 1 is a diagram showing a sheet discharged and a sheet guided to a re-conveying path (b).

[0048] Fig.13 The figures illustrate the movement of the sheet during the rear end avoidance process, including a figure showing a state in which the rear end of the sheet is located in the clamping portion (a), a figure showing a state in which the predetermined cutting portion of the sheet is located on the downstream side compared to the cutter (b), and a figure showing a state in which the rear end of the sheet enters the re-conveying path (c).

[0049] Fig.14 This is a flowchart showing an example of processing executed by the control unit in the modification example.

[0050] Fig.15 This is a timing chart for explaining the timing of sheet feeding, sheet conveyance, and cutting in a modified example. DETAILED DESCRIPTION

[0051] Next, embodiments of the present disclosure will be described in detail with reference to the drawings as appropriate.

[0052] In the following description, the axial direction of the photosensitive drum 51 is referred to as the “axial direction”. In addition, the discharge direction ( Figure 1 The direction of the arrow on the right is called the “discharge direction”.

[0053] like Figure 1 As shown, the image forming device 1 is a laser printer.

[0054] The image forming apparatus 1 includes an apparatus body 2, a supply unit 3, an exposure device 4, a drum cartridge 5, a fixing device 6, a cutter 7, a sheet conveying unit 8, an operation panel PA as an example of an input unit, a sensor SE, and a control unit CU. The exposure device 4 and the drum cartridge 5 are examples of an image forming unit, and form an image on a sheet S.

[0055] The apparatus body 2 has a front cover 21, a discharge tray 22, a first discharge port 23, and a second discharge port 24. The front cover 21 is located on the downstream side of the discharge direction in the apparatus body 2. The discharge tray 22 is formed on the upper surface of the apparatus body 2. The discharge tray 22 is a tray on which discharged sheets are placed.

[0056] The first discharge port 23 is a discharge port for discharging the sheet S to the outside of the apparatus body 2. The first discharge port 23 is located below the second discharge port 24. In other words, the first discharge port 23 is located closer to the fixing device 6 described later than the second discharge port 24. In the present embodiment, the first discharge port 23 discharges the sheet S that has not been cut by the cutter 7 to the outside of the apparatus body 2. The sheet S discharged from the first discharge port 23 is placed on the discharge tray 22.

[0057] The second discharge port 24 is a discharge port different from the first discharge port 23 for discharging the sheet S to the outside of the apparatus body 2. The second discharge port 24 is located above and downstream in the discharge direction compared to the first discharge port 23. In the present embodiment, the second discharge port 24 mainly discharges the sheet S cut by the cutter 7 to the outside of the apparatus body 2. The sheet S discharged from the second discharge port 24 is placed on the discharge tray 22.

[0058] The supply unit 3 is located in the apparatus main body 2 . The supply unit 3 includes a supply tray 31 , a sheet pressing plate 32 , a pickup roller 33 , a separation roller 34 , and a registration roller 35 .

[0059] The supply tray 31 is a tray on which sheets S are placed. The sheet pressing plate 32 pushes the sheets S in the supply tray 31 upward. The pickup roller 33 picks up the sheets S in the supply tray 31. The separation roller 34 separates the sheets S picked up by the pickup roller 33 one by one. The registration roller 35 conveys the sheets S between the photosensitive drum 51 and the transfer roller 53.

[0060] The exposure device 4 is located at the upper part of the device body 2. The exposure device 4 includes a laser light emitting unit, a polygon mirror, a lens, a reflector, etc. (not shown). In the exposure device 4, the laser light (see the dot-dash line) based on the image data emitted from the laser light emitting unit is scanned at high speed on the surface of the photosensitive drum 51, thereby exposing the surface of the photosensitive drum 51.

[0061] The drum cartridge 5 is attachable and detachable to the apparatus main body 2. When the drum cartridge 5 is mounted in the apparatus main body 2, the drum cartridge 5 is located below the exposure device 4. The drum cartridge 5 is attached and detached in a state where the front cover 21 is opened.

[0062] The drum cartridge 5 includes a photosensitive drum 51 , a charger 52 , a transfer roller 53 , a pinch roller 54 , a developing roller 55 , a supply roller 56 , and a toner storage portion 57 .

[0063] The photosensitive drum 51 is rotatable around a drum shaft 51X extending in a first direction. The charger 52 charges the surface of the photosensitive drum 51. The transfer roller 53 is located at a position opposite to the photosensitive drum 51. The transfer roller 53 transfers the toner image formed on the photosensitive drum 51 to the sheet. The charger 52 is a corona charger. The pinch roller 54 is located at a position opposite to the registration roller 35. The pinch roller 54 rotates driven by the rotation of the registration roller 35, thereby conveying the sheet S together with the registration roller 35.

[0064] The developing roller 55 supplies toner to the photosensitive drum 51 in a state of being in contact with the photosensitive drum 51. The supply roller 56 supplies toner in the toner storage portion 57 to the developing roller 55.

[0065] In the drum cartridge 5, the surface of the photosensitive drum 51 is uniformly charged by the charger 52. Then, the surface of the photosensitive drum 51 is exposed by high-speed scanning of the laser from the exposure device 4, thereby forming an electrostatic latent image based on the image data on the photosensitive drum 51. The toner carried on the developing roller 55 is supplied from the developing roller 55 to the electrostatic latent image formed on the photosensitive drum 51. Thus, the electrostatic latent image is visualized, and a toner image is formed on the photosensitive drum 51. Then, the toner image on the photosensitive drum 51 is transferred to the sheet S by conveying the sheet S between the photosensitive drum 51 and the transfer roller 53.

[0066] The fixing device 6 is located at the rear of the drum cartridge 5. The fixing device 6 includes a heating unit 61 as an example of a heating rotating body and a pressure roller 62 as an example of a pressure rotating body. The heating unit 61 includes a halogen heater, a fixing belt, a clamping plate, etc., which are shown with omitted symbols. The clamping belt is clamped between the clamping plate of the heating unit 61 and the pressure roller 62. The clamping portion NP is formed between the pressure roller 62 and the heating unit 61. In the fixing device 6, the toner image transferred to the sheet S is thermally fixed to the sheet S while the sheet S passes between the heating unit 61 and the pressure roller 62.

[0067] The cutter 7 can cut the sheet S, and is located in the upper part of the apparatus main body 2. In the present embodiment, the cutter 7 is arranged in a second conveyance path 82 described later.

[0068] In the image forming apparatus of this embodiment, among the sheet sizes that can be image-formed, only the sheet of letter size, which is a specific size, can be cut by the cutter 7. For example, the following structure is used: A4, letter, legal document, B5, A5, A6, postcard sheets can form images, but among these sheets, only the sheet of letter size, which is a specific size, can be cut after the image is formed. Figure 4As shown, the cutter 7 can cut the letter-sized sheet S at the center of the sheet conveying direction. At least when the length of the sheet S on which the image is formed is shorter than the distance between the second discharge roller 85 and the return roller 86 in the conveying direction, the sheet cannot be conveyed after being cut. Among the above-mentioned sheets, for example, sheets of A4, letter, and legal sizes can be conveyed after being cut because the size in the conveying direction is longer than the distance between the second discharge roller 85 and the return roller 86 in the conveying direction.

[0069] Furthermore, the image forming apparatus of the present embodiment is designed to be able to cut a letter-sized sheet S, which is the smallest sheet size in the conveying direction. That is, when the center of the letter-sized sheet S in the conveying direction is conveyed to the position of the cutter 7, the rear end of the sheet needs to be in a state where it is disengaged from the clamping portion NP. Therefore, the conveying distance D1 of the sheet S from the clamping portion NP to the cutter 7 is designed to be greater than half of the dimension LS of the letter-sized sheet S in the conveying direction (D1>LS / 2). In addition, since the letter-sized sheet S is 215.9mm×279.4mm, half of the dimension LS of the letter-sized sheet in the conveying direction is 139.7mm. Therefore, D1 is set to a value greater than 139.7mm. In addition, in the image forming apparatus of the present embodiment, the image is formed by conveying the sheet in a manner such that the long side of the sheet is along the conveying direction.

[0070] like Figure 2 , Figure 3 As shown, the cutter 7 includes a cutter frame 71 , a slide rail 72 , a fixed blade 73 , a sheet passing portion 74 , a moving blade 75 , a slide holder 76 , a driving pulley 77 , a driven pulley 78 , a pulley belt 79 , and a cutting motor M1 .

[0071] The cutter frame 71 extends in the axial direction. The slide rail 72 is a track formed in the cutter frame 71 and extending in the axial direction. The fixed blade 73 is a flat blade fixed to the cutter frame 71 and extending in the axial direction. The sheet passage portion 74 is a space formed in the cutter frame 71 for the sheet S to pass through. In the present embodiment, the sheet passage portion 74 is formed between the slide rail 72 and the fixed blade 73. The movable blade 75 is a disc-shaped blade, and is rotatably fixed to the slide holder 76.

[0072] The slide holder 76 is engaged with the slide rail 72 and is mounted on the cutter frame 71 so as to be able to slide along the slide rail 72. Figure 2 The slide holder 76 moves from the initial position shown by the solid line to the cutting completion position shown by the dotted line. Figure 2When the slide holder 76 moves along the slide rail 72 to the cutting completion position, one sheet S is clamped by the fixed blade 73 and the movable blade 75 and cut into two sheets. The slide holder 76 returns from the cutting completion position to the initial position before starting to cut the next sheet S.

[0073] The driving pulley 77 is disposed on the other axial side of the cutter frame 71. The driving pulley 77 receives the driving force of the cutting motor M1 and is rotatable in forward and reverse directions.

[0074] The driven pulley 78 is arranged on one side of the axial direction of the cutter frame 71. The pulley belt 79 is hung around the driving pulley 77 and the driven pulley 78. In addition, the sliding holder 76 is fixed to the pulley belt 79. Thus, the sliding holder 76 slides and moves in the axial direction corresponding to the rotation of the pulley belt 79. In detail, when the cutting motor M1 is rotated forward, the sliding holder 76 slides and moves from one side of the axial direction to the other side, and when the cutting motor M1 is reversed, the sliding holder 76 slides and moves from the other side of the axial direction to one side.

[0075] In the cutter 7 , when the sheet S is cut, the cutting motor M1 is rotated forward to move the slide holder 76 located at the initial position toward the cutting completion position.

[0076] Then, the movable blade 75 moves together with the slide holder 76 , so that the sheet S located in the sheet passing portion 74 is sandwiched and cut by the fixed blade 73 and the movable blade 75 .

[0077] When the slide holder 76 is located at the cutting completion position, the cutting motor M1 stops. After the cut sheet S is discharged, the cutting motor M1 is reversed, and the slide holder 76 returns from the cutting completion position to the initial position.

[0078] Return to Figure 1 The sheet conveying section 8 has a function of conveying the sheet S with an image formed thereon to the outside of the apparatus main body 2 or conveying it again to the image forming section. The sheet conveying section 8 includes a first conveying path 81, a second conveying path 82, a re-conveying path 83, a first discharge roller 84, a second discharge roller 85, a return roller 86 as an example of a conveying roller, and a baffle 87.

[0079] The first conveying path 81 is a path for guiding the sheet S with an image formed thereon to the outside of the apparatus body 2. Specifically, the first conveying path 81 is a path from the flapper 87 to the first discharge port 23. In the present embodiment, the first conveying path 81 allows the sheet S not cut by the cutter 7 to pass therethrough.

[0080] The second conveying path 82 is a path different from the first conveying path 81. The second conveying path 82 is a path that guides the sheet on which the image is formed by the image forming unit to the outside of the device body. Specifically, the second conveying path 82 is a path from the baffle 87 to the second discharge port 24. In the present embodiment, the second conveying path 82 is mainly a path for the sheet cut by the cutter 7 to pass. The second conveying path 82 is longer than the first conveying path 81. More specifically, the first conveying path 81 and the second conveying path are curved in the conveying direction, and the sheet S that has passed through the fixing device 6 is discharged from the first discharge port 23 or the second discharge port 24 in the conveying direction opposite to the conveying direction of the sheet S. In addition, the first conveying path 81 is arranged on the inner side of the curve compared with the second conveying path 82, and the second discharge roller 85 and the cutter 7 that are the discharge port of the second conveying path 82 are located above the first discharge roller 84 that is the discharge port of the first conveying path 81. Moreover, the second discharge roller 85 is located on the downstream side of the discharge direction compared with the first discharge roller 84. Therefore, the distance that the sheet S is transported from the nip NP of the fixing device 6 to the second discharge roller 85 of the second transport path 82 is longer than the distance that the sheet S is transported to the first discharge roller 84 of the first transport path 81. Figure 4 As described, in the present embodiment, the conveying distance D1 of the sheet S conveyed from the clamping portion NP to the cutter 7 refers to the distance in the conveying direction from the clamping portion NP to the fixed blade 73 of the cutter 7 that the sheet is conveyed. In the case where the clamping state is formed with the clamping portion NP having a length in the conveying direction, the conveying distance D1 is preferably determined as the distance from the most downstream end in the conveying direction of the clamping portion NP. Moreover, the second conveying path 82 is a structure having a space in a direction orthogonal to the paper surface of the conveyed sheet S (the thickness direction of the sheet). Therefore, depending on the thickness and type of the sheet S, which part in the thickness direction of the sheet S passes through the second conveying path 82 is different. Therefore, the conveying distance D1 of the sheet S conveyed from the clamping portion NP to the cutter 7 is preferably defined by considering the case where the conveying amount is the largest. However, in the case where the deviation of the conveying amount is small, the conveying distance D1 can also be defined by the shortest distance designed from the clamping portion NP to the cutter 7.

[0081] As in Figure 1 As indicated by the dotted line in FIG. 8 , the re-conveying path 83 is a path for guiding the sheet S that has passed through the fixing device 6 toward the image forming unit again. Specifically, it is a path from the flapper 87 to the drum cartridge 5 through the bottom of the fixing device 6 .

[0082] The first discharge roller 84 is arranged in the first conveying path 81, and is a roller that discharges the sheet S to the outside of the device body 2. In the present embodiment, the first discharge roller 84 is a roller pair arranged in the up-down direction, and has a driving roller 84A and a driven roller 84B. The first discharge roller 84 can rotate around an axis parallel to the axial direction. The first discharge roller 84 discharges the sheet S that has not been cut by the cutter 7 to the outside of the device body 2. The first discharge roller 84 is located closer to the fixing device 6 than the second discharge roller 85. The first discharge roller 84 can be driven by the conveying motor M2 (refer to Figure 6 ) is driven to rotate.

[0083] The second discharge roller 85 is arranged on the second conveying path 82, and is a roller that discharges the sheet S to the outside of the device body 2. In the present embodiment, the second discharge roller 85 is a roller pair arranged in the up-down direction, and has a driving roller 85A and a driven roller 85B. The second discharge roller 85 is rotatable about the axial direction. The second discharge roller 85 mainly discharges the sheet S cut by the cutter 7 to the outside of the device body 2. The second discharge roller 85 is located above the first discharge roller 84 and on the downstream side of the discharge direction of the sheet S. The second discharge roller 85 can be rotated by the drive of the conveying motor M2. The conveying speed of the sheet S of the second discharge roller 85 is greater than the conveying speed of the return roller 86.

[0084] The folding roller 86 is arranged on the second conveying path 82, and is a roller for conveying the sheet S. The folding roller 86 is located between the baffle 87 and the cutter 7. In the present embodiment, the folding roller 86 is a roller pair, and has a driving roller 86A and a driven roller 86B. The folding roller 86 can rotate forward and reverse by being driven by the conveying motor M2. When the conveying motor M2 rotates forward, the folding roller 86 conveys the sheet S that has passed the baffle 87 toward the cutter 7. In addition, when the conveying motor M2 rotates reversely, the folding roller 86 conveys the sheet S located on the second conveying path 82 to the re-conveying path 83.

[0085] like Figure 5 As shown, the axial dimension W1 of the driving roller 85A of the second discharge roller 85 is larger than half the width WS of the maximum width of the sheet S that the image forming apparatus 1 can convey (W1>WS / 2). In this embodiment, the maximum width that the image forming apparatus 1 can convey is 215.9 mm.

[0086] Similarly, the axial dimension W2 of the driven roller 85B of the second discharge roller 85 is larger than half the width WS of the maximum width of the sheet that can be transported by the image forming apparatus 1 (W2>WS / 2). In addition, the axial dimension W1 of the driving roller 85A of the second discharge roller 85 is larger than the width WS of the maximum width of the sheet S that can be transported by the image forming apparatus 1 (W1>WS). In addition, the axial dimension W2 of the driven roller 85B of the second discharge roller 85 is smaller than the width WS of the maximum width of the sheet S that can be transported by the image forming apparatus 1 (W2<WS).

[0087] The axial dimension W3 of the driving roller 86A of the folding roller 86 is larger than half the width WS of the maximum width of the sheet S that can be conveyed by the image forming apparatus 1 ( W3 > WS / 2).

[0088] Similarly, the axial dimension W4 of the driven roller 86B of the folding roller 86 is larger than half the width WS of the maximum width of the sheet that can be conveyed by the image forming apparatus 1 (W4>WS / 2). In addition, the axial dimension W3 of the driving roller 86A of the folding roller 86 is larger than the width WS of the maximum width of the sheet S that can be conveyed by the image forming apparatus 1 (W3>WS). In addition, the axial dimension W4 of the driven roller 86B of the folding roller 86 is smaller than the width WS of the maximum width of the sheet S that can be conveyed by the image forming apparatus 1 (W4<WS).

[0089] The flapper 87 is located at the branching portion between the first conveying path 81 and the second conveying path 82. The flapper 87 can be moved to Figure 1 The first position shown by the solid line and Figure 1 The flapper 87 guides the sheet S that has passed through the fixing device 6 to the first conveying path 81 when located at the first position. The flapper 87 guides the sheet S that has passed through the fixing device 6 to the second conveying path 82 when located at the second position.

[0090] The sensor SE is arranged in the conveying path of the sheet S and is a sensor capable of detecting the presence or absence of the sheet S. Specifically, the sensor SE includes a first sensor SE1, a second sensor SE2, and a third sensor SE3. The first sensor SE1 is located between the separation roller 34 and the registration roller 35 in the conveying direction of the sheet. The first sensor SE1 is located just in front of the registration roller 35. The second sensor SE2 is located between the registration roller 35 and the photosensitive drum 51 in the conveying direction of the sheet. The third sensor SE3 is located between the fixing device 6 and the baffle 87 in the conveying direction of the sheet.

[0091] The operation panel PA is located on the outer surface of the apparatus body 2. The operation panel PA allows the user to input commands for image formation, cutting of the sheet S, and the like. In the present embodiment, for example, the operation panel PA allows the user to input a cutting position of the sheet S.

[0092] The control unit CU includes a CPU (Central Processing Unit), a RAM (Random access Memory), a ROM (Read only Memory), and an input / output circuit, and performs various calculations based on programs and data stored in the ROM, etc., thereby controlling the image forming apparatus 1 .

[0093] like Figure 6 As shown, the control unit CU is electrically connected to the first sensor SE1, the second sensor SE2 and the third sensor SE3 and can receive detection signals from each of them. The control unit CU controls the pickup roller 33, the cutting motor M1, the conveying motor M2 and the flapper 87 based on information received from the operation panel PA and the sensors.

[0094] In principle, the control unit CU conveys the sheet S to the first conveying path 81 when the cutter 7 does not cut the sheet S, and conveys the sheet to the second conveying path 82 when the cutter 7 cuts the sheet S.

[0095] When the control unit CU conveys the sheet S toward the cutter 7, the control unit CU starts the rotation of the return roller 86 after the leading end of the sheet S in the conveying direction contacts the return roller 86. Specifically, the control unit CU receives a detection signal indicating that the leading end of the sheet S is detected by the third sensor SE3. After a predetermined time has passed since the detection signal from the third sensor SE3 was received, the control unit CU causes the conveying motor M2 to rotate forward and starts the rotation of the return roller 86. The predetermined time is a time sufficient for the leading end of the sheet S to contact the return roller 86 and correct the inclined travel of the sheet S.

[0096] like Figure 4 As shown, when the control unit CU receives an instruction to cut the sheet S, the sheet S is cut by the cutter 7 when the dimension L1 in the conveying direction from the predetermined cutting position PP of the sheet S to the rear end position of the sheet S is shorter than the conveying distance D1 of the sheet S from the clamping portion NP to the cutter 7. That is, when the dimension L1 in the conveying direction from the predetermined cutting position PP of the sheet S to the rear end position of the sheet S is greater than the conveying distance D1 of the sheet S from the clamping portion NP to the cutter 7, the control unit CU does not cut the sheet S by the cutter 7.

[0097] The control unit CU cuts the sheet S based on the command input to the operation panel PA. Specifically, when the control unit CU receives the command to cut the sheet S, the sheet S is cut by the cutter 7 while the conveyance of the sheet S is stopped. For example, when a command to cut a letter-sized sheet S having a size of 215.9 mm in the conveyance direction into half is received, after being cut, there are two sheets S having a size of 139.7 mm in the conveyance direction.

[0098] The control unit CU can obtain the size of the sheet S in the conveying direction based on the detection signal from the sensor SE. Specifically, the control unit CU only needs to calculate the size of the sheet S in the conveying direction based on the time it takes for the sheet S to pass through the first sensor SE1. In the present embodiment, the control unit CU obtains the size of the sheet S based on the detection signal from the first sensor SE1, but may also obtain the size of the sheet S based on the detection signal of other sensors (second sensor SE2, third sensor SE3, etc.).

[0099] When the control unit CU determines based on the detection signal from the sensor SE that the size of the sheet S in the conveying direction is smaller than a predetermined value, it conveys the sheet S to the second conveying path 82 and discharges the sheet S to the outside of the apparatus body 2 without cutting it.

[0100] In addition, when the control unit CU determines that the size of the sheet S in the conveying direction of the sheet contained in the received printing job (hereinafter referred to as "job") is smaller than a specified value, the sheet S is conveyed to the second conveying path 82 and discharged to the outside of the device body 2 without cutting the sheet S.

[0101] In this way, when the control unit CU determines that the size of the sheet S in the conveying direction is smaller than a specified value based on the detection signal from the sensor SE and the information of the received job, the sheet S is conveyed to the second conveying path 82 even if the sheet S is not cut by the cutter 7.

[0102] When the control unit CU receives an instruction to cut a plurality of sheets S, it starts feeding the next sheet S before the preceding sheet S is cut. The control unit CU starts feeding the sheet S by driving the pickup roller 33. When the control unit CU receives an instruction to cut a plurality of sheets S, it conveys the sheet with a predetermined interval between the rear end of the preceding sheet S and the front end of the next sheet.

[0103] Next, refer to Figure 7 , an example of the processing performed by the control unit CU that receives the job is described.

[0104] When the control unit CU determines that a job has been received ( S1 , Yes), it determines whether to cut the sheet S based on the command input through the operation panel PA and the information of the job ( S2 ).

[0105] In step S2, when the control unit CU determines that the sheet S is to be cut (S2, yes), it determines whether the dimension L1 from the predetermined cutting point PP of the sheet S to the rear end position is longer than D1 stored in ROM, etc., which is the distance from the clamping part NP to the cutter 7 (L1>D1?) (S3).

[0106] If the sheet S is not determined to be cut in step S2 (S2, No), or if the dimension L1 from the predetermined cutting position PP to the rear end position of the sheet S is determined to be longer than the dimension from the clamping portion NP to the cutter 7 (L1>D1) (S3, Yes) in step S3, the control unit CU determines whether the dimension of the sheet S is greater than or equal to a predetermined value (half the letter size 139.7 mm) (S4). The control unit CU determines the dimension of the sheet S by a method of determining based on the information of the received job and a method of acquiring the dimension of the sheet S based on the detection result of the sensor SE.

[0107] In step S4, when the control unit CU determines that the size of the sheet S in the conveying direction is greater than the specified value (137.9 mm) (S4, Yes), the baffle 87 is located at the first position, the sheet S is guided to the first conveying path 81, and the conveying motor M2 is rotated forward (S5). As a result, the first discharge roller 84 is driven to discharge the sheet from the first discharge port 23.

[0108] After step S5, the control unit CU determines whether the received job has been completed (S7). If the received job has been completed (S7, Yes), the processing ends; if the received job has not been completed (S7, No), the process returns to step S2.

[0109] In step S4, when the control unit CU does not determine that the size of the sheet S in the conveying direction is greater than the specified value (137.9 mm) (S4, No), it places the baffle 87 in the second position, guides the sheet S to the second conveying path 82, and rotates the conveying motor M2 forward (S6).

[0110] After step S6, the control unit CU determines whether the received job has been completed (S7). If the received job has been completed (S7, Yes), the processing ends; if the received job has not been completed (S7, No), the process returns to step S2.

[0111] On the other hand, when it is determined in step S3 that the dimension L1 from the predetermined cutting point PP of the sheet S to the rear end position is not longer than the dimension from the clamping part NP to the cutter 7 (L1≤D1) (S3, No), the control unit CU places the baffle 87 in the second position and guides the sheet S to the second conveying path 82 (S8).

[0112] After step S8, the control unit CU determines whether a predetermined time has passed since the detection signal from the third sensor SE3 was received (S9).

[0113] In step S9, if the control unit CU does not determine that the predetermined time has passed since the detection signal of the third sensor SE3 was received (S9, No), it waits until the predetermined time has passed since the detection signal of the third sensor SE3 was received. When the predetermined time has passed since the detection signal of the third sensor SE3 was received, the leading end of the sheet S contacts the return roller 86 and the inclined travel is corrected.

[0114] When the control unit CU determines that a predetermined time has passed since the detection signal from the third sensor SE3 was received (S9, Yes), it drives the conveying motor M2 to rotate forward, thereby rotating the folding roller 86 forward and conveying the sheet S to the cutter 7 (S10).

[0115] After step 10, when the planned cutting position PP of the sheet S is located at the cutter 7 after a predetermined time has passed since the conveying motor M2 started to rotate forward, the conveying motor M2 is temporarily stopped and the cutting motor M1 is rotated forward (S11).

[0116] After step S11, the control unit CU determines whether there is a job for the next sheet S (S12). If it is determined that there is a job for the next sheet S (S12, Yes), the supply of the next sheet S is started (S13), and the process moves to S14. If it is not determined that there is a job for the next sheet S (S12, Yes), the next sheet S is not supplied, and the process moves to S14.

[0117] After step S12 or step S13 , the control unit CU stops the cutting motor M1 and rotates the conveying motor M2 forward after a predetermined time has passed since the start of cutting ( S14 ). As a result, the slide holder 76 of the cutter 7 stops at the cutting completion position, and the sheet S is discharged by the second discharge roller 85 .

[0118] After step S14, the control unit CU stops the conveying motor M2 and reverses the cutting motor M1 (S15). As a result, the slide holder 76 of the cutter 7 returns to the initial position.

[0119] After step S15, the control unit CU determines whether the received job has been completed (S7). If the received job has been completed (S7, Yes), the processing ends; if the received job has not been completed (S7, No), the process returns to step S2.

[0120] Next, refer to Figure 8 The following describes the actions of picking up a sheet S when receiving a job of cutting a plurality of sheets S, conveying the sheet S by the conveying motor M2 (the return roller 86 and the second discharge roller 85), and cutting the sheet S by the cutting motor M1.

[0121] The control unit CU drives the pickup roller 33 to start feeding the first sheet S (time t1 ). The fed first sheet S is image-formed and is conveyed toward the cutter 7 .

[0122] After a predetermined time has passed since the third sensor SE3 received the detection signal, the control unit CU rotates the conveyance motor M2 forward to convey the sheet S to the cutter 7 (time t2 ).

[0123] After a predetermined time has passed since the conveying motor M2 was rotated forward, the control unit CU temporarily stops the conveying motor M2 and rotates the cutting motor M1 forward (time t3 ). Thus, the sheet S is cut while it is stopped.

[0124] After the cutting motor M1 is rotated forward and before the cutting of the sheet S is completed, the control unit CU drives the pickup roller 33 to start feeding the second sheet S (time t4). Thus, the second sheet S starts to be conveyed while the first sheet S is being cut.

[0125] After a predetermined time has passed since the start of cutting, the control unit CU stops the cutting motor M1 and rotates the conveying motor M2 forward (time t5 ). As a result, the cut portions of the first sheet S are discharged.

[0126] After a predetermined time has passed from time t5, the control unit CU stops the conveying motor M2 and reverses the cutting motor M1 (time t6). As a result, the slide holder 76 of the cutter 7 starts to move from the cutting completion position toward the initial position.

[0127] When the slide holder 76 returns to the initial position due to the lapse of the prescribed time from time t6, the control unit CU stops the cutting motor M1 (time t7). At this time, if the prescribed time has passed since the third sensor SE3 received the detection signal of the second sheet S, the conveying motor M2 is rotated forward at the same time. If the prescribed time has not passed, the conveying motor M2 is rotated forward after the prescribed time has passed.

[0128] The control unit CU also performs the operation of conveying and cutting the second and third sheets S at the same timing as the first sheet S.

[0129] Based on the above, the following effects can be obtained in this embodiment.

[0130] In the image forming apparatus 1, the second discharge roller 85 is located on the downstream side of the discharge direction compared with the first discharge roller 84. Fig. 9 As shown in FIG. 1 , the cut sheet S is discharged to the downstream side in the discharge direction compared to the uncut sheet S. As a result, the cut sheet S can be easily taken out.

[0131] In addition, the second discharge port 24 is located downstream of the first discharge port 23 in the discharge direction. Therefore, the cut sheet S is discharged downstream of the uncut sheet S in the discharge direction. As a result, the cut sheet S can be easily taken out.

[0132] In addition, the image forming apparatus 1 includes a flapper 87 that can be moved to a first position for guiding the sheet S that has passed through the fixing device 6 to the first conveying path 81 and a second position for guiding the sheet S that has passed through the fixing device 6 to the second conveying path 82. Therefore, the flapper 87 can guide the sheet S to either the first conveying path 81 or the second conveying path 82.

[0133] Here, the cutter 7 is located at a position more than a predetermined distance away from the fixing device 6 in order to cut the sheet S after the rear end of the sheet S has passed through the fixing device 6. Therefore, when the first discharge roller 84 is located at a position farther from the fixing device 6 than the second discharge roller 85 that discharges the cut sheet S, the device body becomes larger. However, in the present embodiment, the first discharge roller 84 is located at a position closer to the fixing device 6 than the second discharge roller 85, so that the size of the device body 2 can be suppressed. Similarly, by locating the first discharge port 23 at a position closer to the fixing device 6 than the second discharge port 24, the device body 2 can be miniaturized.

[0134] In addition, the axial dimensions W1 and W2 of the second discharge roller 85 and the axial dimensions W3 and W4 of the folding roller 86 are larger than half WS / 2 of the width of the maximum width of the sheet S that can be conveyed by the image forming apparatus 1 (W1>WS / 2, W2>WS / 2, W3>WS / 2, W4>WS / 2). Therefore, when the sheet S is cut, the second discharge roller 85 and the folding roller 86 hold the sheet S in a wide area in the width direction of the sheet S, thereby suppressing positional deviation of the sheet S when cut.

[0135] In addition, at least one of the axial dimension W1 of the second discharge roller 85 and the axial dimension W3 of the folding roller 86 is larger than the width WS of the maximum width of the sheet S that can be conveyed by the image forming apparatus 1. Therefore, when the sheet S is cut, the second discharge roller 85 or the folding roller 86 holds the sheet S in a wider area in the width direction of the sheet S, thereby suppressing positional deviation of the sheet S when cutting.

[0136] In addition, the control unit CU obtains the size of the sheet S in the conveying direction based on the detection signal from the sensor SE or the information of the job, and when it is determined that the size of the sheet S in the conveying direction is smaller than the specified value (139.7 mm), the sheet S is conveyed to the second conveying path 82, and the sheet S is discharged to the outside of the apparatus body 2 without being cut. Therefore, when a small-sized sheet S is discharged, the sheet S is discharged through the second conveying path 82, so that the small-sized sheet S can be easily taken out.

[0137] In addition, if Figure 4 As shown in FIG. 1 , the conveying distance D1 of the sheet S from the clamping portion NP to the cutter 7 is greater than half of the dimension LS (279.4 mm) of the letter-sized sheet S in the conveying direction (D1>LS / 2=139.7 mm). Therefore, the sheet S can be cut while the entire letter-sized sheet S has passed through the clamping portion NP. As a result, even if the sheet S is cut while the conveyance of the sheet S is stopped, it is possible to prevent the sheet S from being excessively heated or pressurized in the clamping portion NP.

[0138] Moreover, when receiving the instruction to cut the sheet S, the control unit CU cuts the sheet S in a state where the conveyance of the sheet S is stopped. Therefore, the sheet S can be cut straightly in the axial direction.

[0139] Furthermore, when the control unit CU receives an instruction to cut the sheet S, the sheet S is cut by the cutter 7 when the dimension L1 in the conveying direction from the predetermined cutting position PP of the sheet S to the rear end position of the sheet S is shorter than the conveying distance D1 of the sheet S from the clamping portion NP to the cutter 7. Thus, when the dimension L1 in the conveying direction from the predetermined cutting position PP of the sheet S to the rear end position of the sheet S is greater than the conveying distance D1 of the sheet S from the clamping portion NP to the cutter 7, the control unit CU does not cut the sheet S by the cutter 7, thereby preventing the sheet S from being excessively heated or pressurized in the clamping portion NP.

[0140] Furthermore, when the control unit CU conveys the sheet S toward the cutter 7, the control unit CU starts the rotation of the folding roller 86 after the leading end of the sheet S in the conveying direction contacts the folding roller 86. Therefore, even when the sheet S is conveyed while being obliquely advanced with respect to the conveying direction, the oblique advancement can be suppressed by bringing the sheet S into contact with the folding roller 86.

[0141] The conveying speed of the second discharge roller 85 is greater than the conveying speed of the folding roller 86. Therefore, when the sheet S contacts both the second discharge roller 85 and the folding roller 86, the sheet S is stretched by the second discharge roller 85 and the folding roller 86, so that it is possible to suppress the slack of the sheet S between the folding roller 86 and the second discharge roller 85. In addition, after the sheet S is cut, the cut sheets S contact each other, and interference between the sheets can be suppressed.

[0142] Furthermore, when receiving a command to cut a plurality of sheets S, the control unit CU starts feeding the next sheet S before the preceding sheet S is cut. Therefore, even when cutting a plurality of sheets, it is possible to suppress a delay in the completion of the job.

[0143] Furthermore, when receiving a command to cut a plurality of sheets S, the control unit CU conveys the sheets S with a predetermined interval between the rear end of the preceding sheet S and the front end of the next sheet S. Therefore, interference between the preceding sheet S and the next sheet S can be suppressed.

[0144] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments described above. The specific configuration can be appropriately changed within the scope of the present disclosure.

[0145] In the above-described embodiment, the sheets S discharged from the first discharge port 23 and the second discharge port 24 are both placed on one discharge tray 22 , but the present invention is not limited to this structure.

[0146] For example, Fig.10 The image forming apparatus 1A shown in the figure is provided with a discharge tray 22 as an example of a first discharge tray and a second discharge tray 25. The discharge tray 22 can load the sheet S discharged through the first conveying path 81. The second discharge tray 25 can load the sheet S discharged through the second conveying path 82. The second discharge tray 25 is provided outside the second discharge port 24. Therefore, in the image forming apparatus 1A, the sheet S discharged from the first conveying path 81 and the sheet S discharged from the second conveying path 82 can be stored in different trays. As a result, the cut sheet S can be easily taken out.

[0147] In the above-mentioned embodiment, the sheet S discharged from the first discharge port 23 and the second discharge port 24 is placed on the discharge tray 22, but it is also possible to have a structure without a discharge tray. Although not shown in the figure, for example, the sheet S discharged from the first discharge port 23 and the second discharge port 24 may be directly discharged onto a table, a floor, etc., and the sheet S may be placed on the table or the floor.

[0148] In the above-mentioned embodiment, the image forming apparatus 1 is configured without a scanner unit, but the present invention is not limited to this configuration. Fig.11 The image forming apparatus 1B shown in the figure further includes a scanner unit 9. The scanner unit 9 is a device for reading characters and images on the sheet S and the like. In the image forming apparatus 1B, since the scanner unit 9 is arranged above the discharge tray 22, the gap for taking out the sheet S is narrow. If the cut sheet S and the uncut sheet S are discharged to the same position, it is very difficult to take out the sheet S. However, by positioning the second discharge roller 85 on the downstream side of the discharge direction relative to the first discharge roller 84 and the second discharge port 24 on the downstream side of the discharge direction relative to the first discharge port 23, the cut sheet S is discharged to the downstream side of the conveying direction relative to the uncut sheet S, and the cut sheet S is easily taken out.

[0149] In the above-mentioned embodiment, the conveying distance D1 of the sheet S from the clamping portion NP to the cutter 7 is larger than half the dimension LS (139.7 mm) of the letter-sized sheet S in the conveying direction, but it can also be based on sheets S other than letter-sized sheets.

[0150] For example, the following structure may be adopted: based on the A4 size (210 mm×297 mm), the conveying distance D1 of the sheet S from the clamping portion NP to the cutter 7 is larger than half the dimension LS (148.5 mm) of the A4 size sheet S in the conveying direction.

[0151] Thus, in addition to the letter size, the A4 size sheet S can be cut after the sheet S has passed through the clamping portion NP as a whole. As a result, even if the sheet S is cut in a state where the conveyance of the sheet S is stopped, it is possible to prevent the sheet S from being excessively heated or pressurized in the clamping portion NP. In other words, the fixing device 6 and the cutter 7 are arranged so that the conveyance distance D1 of the sheet S conveyed from the clamping portion NP to the cutter 7 is greater than half of the dimension in the conveyance direction of the sheet size that is desired to be cut.

[0152] For example, the following structure may be adopted: based on the legal document size (215.9 mm × 355.6 mm), the conveying distance D1 of the sheet S from the clamping portion NP to the cutter 7 is larger than half the dimension LS (177.8 mm) of the sheet S of the legal document size in the conveying direction.

[0153] Thus, the legal document size sheet S can be cut while the entire sheet S passes through the nip NP. Therefore, even if the sheet S is cut while the conveyance of the sheet S is stopped, it is possible to prevent the sheet S from being excessively heated or pressurized in the nip NP.

[0154] In the above-described embodiment, the cutter 7 cuts one sheet S into two sheets and discharges both sheets immediately after cutting, but the present invention is not limited to this configuration.

[0155] For example, Fig.12 As shown in (a) and (b), the control unit CU can also be set to the following structure: a sheet S is cut into two sheets (S1, S2) by using the cutter 7, and the sheet S2 on the upstream side of the conveying direction of the cut sheet S is conveyed to the re-conveying path 83 by reversing the return roller 86.

[0156] Specifically, if Fig.12 As shown in (a) of FIG. 12 , the control unit CU uses the cutter 7 to cut a sheet S into two sheets (S1, S2). As shown in FIG. 12 (b), the downstream sheet S1 of the cut sheet S is discharged from the second discharge port 24 after cutting. The upstream sheet S2 of the cut sheet S is conveyed to the re-conveying path 83. Fig.12 As shown by the double-dashed line in (b), the sheet S2 on the upstream side is held on the re-conveying path 83. When the control unit CU receives a job corresponding to the sheet S2, it conveys the held sheet S2 to the image forming unit to perform image formation. If the sheet S2 is still held on the re-conveying path 83, the control unit CU discharges the sheet S2 without performing image formation if it determines that the received job cannot be performed. As described above, in this Fig.12 In the illustrated embodiment, the sheet S2 on the upstream side among the cut sheets S can be re-conveyed to the re-conveyance path 83 to perform image formation again.

[0157] In the above-mentioned embodiment, the control unit CU has the following structure: the sheet S is not cut when the dimension in the conveying direction from the predetermined cutting position PP of the sheet S to the rear end position EN of the sheet is longer than the conveying distance D1 of the sheet S from the position of the clamping part NP to the cutter 7, but it is not limited to this structure.

[0158] For example, the control unit CU may be configured to cut the sheet S even when the dimension in the conveying direction from the predetermined cutting position PP of the sheet S to the rear end position EN of the sheet S is longer than the conveying distance D1 of the sheet S from the position of the clamping portion NP to the cutter 7 .

[0159] like Fig.13 As shown in (a), when the distance from the planned cutting position PP of the sheet S to the rear end position EN is longer than the conveying distance D1, the control unit CU performs the rear end avoidance control. Fig.13 In (a), (b), and (c) of FIG. 1 , the planned cutting portion PP is indicated by a black triangle.

[0160] In the back-end avoidance control, such as Fig.13 As shown in (b), the sheet S is conveyed until the predetermined cutting position PP of the sheet S is located downstream of the cutter 7 and the rear end EN is located downstream of the path from the fixing device 6 to the baffle 87 and the branch point BP of the re-conveying path. Fig.13 As shown in (c), the folding roller 86 is reversed to place the rear end position EN of the sheet S in the re-conveying path 83, and the sheet S is cut in a state where the rear end position EN of the sheet S enters the re-conveying path.

[0161] Thus, even when the conveying distance D1 is shorter than the dimension from the predetermined cutting position PP of the sheet to the rear end position EN of the sheet, the sheet S can be cut with the rear end position EN of the sheet S having passed through the fixing device 6. Therefore, when the predetermined cutting position PP of the sheet S is cut by the cutter 7, it is possible to prevent the sheet S from being sandwiched between the heating unit 61 and the pressure roller 62. As a result, it is possible to prevent the image forming apparatus 1 from being enlarged.

[0162] In the above-described embodiment, the control unit CU is configured to start feeding the next sheet S before the cutting of the preceding sheet S is completed when receiving a command to cut a plurality of sheets S, but the present invention is not limited to this configuration.

[0163] For example, the control unit CU can also be set to the following structure: when receiving an instruction to cut multiple sheets S, the movable blade 75 is moved from the initial position along the width direction of the sheet S to cut the sheet S, and after the cutting of the preceding sheet S is completed, the supply of the next sheet S is started before the movable blade 75 reaches the initial position.

[0164] Specifically, if Fig.14As shown, after the control unit CU reverses the cutting motor M1 in step S15, if there is a job for the next sheet S (S22, yes), the supply of the next sheet S is started (S23). Then, after step S23, if the slide holder 76 of the cutter 7 returns to the initial position, the control unit CU stops the cutting motor M1.

[0165] Reference Fig.15 , the actions of picking up the sheet S when receiving a job of cutting multiple sheets S, conveying the sheet S by the conveying motor M2 (returning roller 86 and second discharge roller 85), and cutting the sheet S by the cutting motor M1 are explained.

[0166] The control unit CU drives the pickup roller 33 to start feeding the first sheet S (time t21 ). The fed first sheet S is image-formed and is conveyed toward the cutter 7 .

[0167] After a predetermined time has passed since the third sensor SE3 received the detection signal, the control unit CU controls the conveyance motor M2 to rotate forward to convey the sheet S to the cutter 7 (time t22 ).

[0168] After a predetermined time has passed since the conveying motor M2 was rotated forward, the control unit CU temporarily stops the conveying motor M2 and rotates the cutting motor M1 forward (time t23 ). Thus, the sheet S is cut while it is stopped.

[0169] After a predetermined time has passed since the start of cutting, the control unit CU stops the cutting motor M1 and rotates the conveying motor M2 forward (time t24 ). As a result, the cut portions of the first sheet S are discharged.

[0170] After a predetermined time has passed from time t24, the control unit CU stops the conveying motor M2 and reverses the cutting motor M1 (time t25). As a result, the movable blade 75 of the cutter 7 starts to move from the cutting completion position toward the initial position.

[0171] After the control unit CU reverses the cutter motor M1 and before the moving blade 75 reaches the home position, it drives the pickup roller 33 to start feeding the second sheet S (time t26 ). Thus, the second sheet S starts to be conveyed while the moving blade 75 is moving.

[0172] When a predetermined time has passed from time t25 and the slide holder 76 has returned to the initial position, the control unit CU stops the cutting motor M1 ( t27 ).

[0173] The control unit CU also performs the operation of conveying and cutting the second and third sheets S at the same timing as the first sheet S.

[0174] Even in the configuration described above, the conveyance of the next sheet S starts before the movable blade 75 reaches the home position. Therefore, even when a plurality of sheets S are cut, a delay in the completion of the job can be suppressed.

[0175] In the above-described embodiment, the cutter 7 is disposed in the second conveying path 82 , but the present invention is not limited to this configuration. For example, the cutter 7 may be disposed between the flapper 87 and the fixing device 6 .

[0176] In the above-described embodiment, the operation panel PA is exemplified as the input unit, but a configuration in which a print command or a cut command is input via a computer or a network may be adopted.

[0177] In the above-described embodiment, the first discharge roller 84 , the second discharge roller 85 , and the return roller 86 are each a pair of rollers consisting of two rollers, but the present invention is not limited thereto and each may consist of one roller or three or more rollers.

[0178] In the above embodiment, the maximum width that the image forming apparatus 1 can transport is set to 215.9 mm using the letter size (215.9 mm×279.4 mm) as an example, but the size is not limited to this size and may be based on the A4 size (210 mm×297 mm) or the A3 size (297 mm×420 mm).

[0179] In the above-mentioned embodiment, the image forming device is a laser printer that forms a monochrome image, but it is not limited to this. For example, the image forming device may also be a printer that forms a color image. In addition, the image forming device is not limited to a printer. For example, the image forming device may also be a copier, a multifunction machine, etc.

[0180] The respective elements described in the above-mentioned embodiment and modified examples may be arbitrarily combined and implemented.

[0181] Explanation of symbols

[0182] 1 Image forming device

[0183] 2 Device body

[0184] 3 Supply Department

[0185] 4 Exposure device

[0186] 5 Drum Box

[0187] 6 Fixing device

[0188] 7 Cutter

[0189] 8 Sheet conveying unit

[0190] 22 Ejection tray

[0191] 23 Exit 1

[0192] 24 Second row exit

[0193] 51 Photosensitive drum

[0194] 61 Heating unit

[0195] 62 Pressure roller

[0196] 81 First conveying path

[0197] 82 Second conveying path

[0198] 83 Re-transportation path

[0199] 84 First discharge roller

[0200] 85 Second discharge roller

[0201] 86 Folding roller

[0202] 87 Baffle

[0203] CU Control Unit

[0204] D1 Conveying distance

[0205] NP clamping part

[0206] PA operation panel

[0207] PP Scheduled cutting area

[0208] S sheet.

Claims

1. An image forming device, characterized in that: have: Device body; an image forming unit that forms an image on a sheet; a fixing device including a heating rotating body and a pressing rotating body forming a nip portion with the heating rotating body, the fixing device fixing the image to the sheet; as well as a cutter, which is arranged on the downstream side of the sheet conveying direction of the fixing device and can cut the sheet, The cutter can cut the sheet at a central position in the conveying direction of the sheet. The distance that the sheet is conveyed from the gripping portion to the cutter is greater than half of the dimension of the sheet to be cut in the conveying direction.

2. The image forming apparatus according to claim 1, wherein: The cutter is capable of cutting at least an A4-sized sheet at a central position in the conveying direction of the sheet. In the conveying direction, the distance by which the sheet is conveyed from the gripping portion to the cutter is greater than half of a dimension of an A4-size sheet in the conveying direction.

3. The image forming apparatus according to claim 1, wherein: The cutter is capable of cutting at least a letter-sized sheet at a central position in the conveying direction of the sheet. In the conveying direction, the distance that the sheet is conveyed from the gripping portion to the cutter is greater than half of a dimension of a legal-size sheet in the conveying direction.

4. The image forming apparatus according to any one of claims 1 to 3, characterized in that: Also available: a conveying roller, which is located upstream of the cutter in the conveying direction of the sheet and is rotatable about the axial direction, and which conveys the sheet toward the cutter; as well as a discharge roller, which is located on the downstream side of the cutter in the conveying direction of the sheet, is rotatable about the axial direction, and discharges the sheet to the outside of the apparatus body, The conveying roller and the discharge roller have a dimension in the axial direction that is larger than half of a width of a sheet having a maximum width that can be conveyed by the image forming apparatus.

5. The image forming apparatus according to claim 4, wherein: A dimension of at least one of the conveying roller and the discharge roller in the axial direction is larger than a width of a sheet having a maximum width that can be conveyed by the image forming apparatus.

6. The image forming apparatus according to any one of claims 1 to 3, characterized in that: Also available: a conveying roller located on an upstream side of the cutter in a conveying direction of the sheet and conveying the sheet toward the cutter; a re-conveying path that guides the sheet that has passed through the fixing device toward the image forming section again; as well as Control Department, The control unit uses the cutter to cut one sheet into two sheets. The control unit can convey the cut sheets on the upstream side in the conveying direction to the re-conveying path by reversing the conveying roller.

7. The image forming apparatus according to any one of claims 1 to 3, characterized in that: It also has a control unit. The control unit cuts the sheet while stopping the conveyance of the sheet, when receiving the instruction to cut the sheet.

8. The image forming apparatus according to any one of claims 1 to 3, characterized in that: have: a first conveying path for guiding the sheet fixed by the fixing device to the outside of the device body; a second conveying path which is different from the first conveying path and guides the sheet fixed by the fixing device to the outside of the device body; as well as Control Department, the control unit conveys the sheet to the first conveying path without cutting the sheet by the cutter, The control section conveys the sheet to the second conveyance path when the sheet is cut by the cutter.

9. The image forming apparatus according to claim 8, wherein: The apparatus further comprises: a first discharge port for discharging the sheet from the first conveying path to the outside of the apparatus body; and a second discharge port for discharging the sheet from the second conveying path to the outside of the apparatus body, The first discharge outlet is located closer to the fixing device than the second discharge outlet.

10. The image forming apparatus according to any one of claims 1 to 3, characterized in that: Equipped with a control unit, When the control unit receives an instruction to cut the sheet, the sheet is cut by the cutter when the dimension in the conveying direction from the predetermined cutting position of the sheet to the rear end position of the sheet is shorter than the conveying distance of the sheet from the clamping unit to the cutter.

11. The image forming apparatus according to claim 10, wherein: An input section is provided for inputting the cut portion of the sheet, The control unit cuts the sheet based on a command input to the input unit.

12. The image forming apparatus according to any one of claims 1 to 3, characterized in that: Also available: a conveying roller which is located on an upstream side of the cutter in a conveying direction of the sheet and conveys the sheet to the cutter; and Control Department, When the sheet is conveyed to the cutter, the control unit starts the rotation of the conveying roller after the leading end of the sheet in the conveying direction comes into contact with the conveying roller.

13. The image forming apparatus according to any one of claims 1 to 3, characterized in that: Also available: a conveying roller located on an upstream side of the cutter in a conveying direction of the sheet and conveying the sheet toward the cutter; and a discharge roller which is located on the downstream side of the cutter in the conveying direction of the sheet and discharges the sheet to the outside of the apparatus body, A conveying speed of the discharge roller is greater than a conveying speed of the conveying roller.

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