Image forming apparatus

Abstract

The present disclosure is an image forming apparatus including: a housing including a stacking portion and an upstream wall; a transfer portion; a fixing device housed in the housing; an ejection member configured to eject a sheet on which a toner image is fixed by the fixing device from an inside of the housing to an outside in a sheet ejection direction; a reverse member configured to perform reverse conveyance on a sheet that has passed through the transfer portion and the fixing device; a first conveyance guide provided to separate a first conveyance path from a second conveyance path; a fan configured to generate an air flow; a first air path forming portion including a first opening formed in the first conveyance guide; and a second air path forming portion including a second opening formed in the upstream wall.

Description

Technical Field

[0001] This disclosure relates to an image forming apparatus for forming an image on a sheet. Background Technology

[0002] Japanese Patent Publication No. 2022-124716 discloses an image forming apparatus comprising: a stacking surface on which a sheet discharged from the image forming apparatus is stacked; a stacking wall for adjusting the position of the trailing edge of the sheet stacked on the stacking surface; and a blower fan for cooling the sheet on the stacking surface via an air outlet formed in the stacking wall. Summary of the Invention

[0003] This disclosure provides an image forming apparatus capable of adequately cooling a sheet.

[0004] One aspect of this disclosure provides an image forming apparatus comprising: a housing including a stacking section and an upstream wall, wherein a sheet discharged along a sheet discharge direction intersecting a vertical direction is stacked on the stacking section, the upstream wall being disposed upstream of the stacking section in the sheet discharge direction and facing the end of the sheet stacked on the stacking section; a transfer section, at which a toner image is transferred onto the sheet; a fixing device housed within the housing and configured to heat the toner image on the sheet to fix the toner image onto the sheet; an ejection member configured to eject the sheet with the toner image fixed by the fixing device from the inside to the outside of the housing along the sheet discharge direction; and a reversing member configured to reverse the sheet that has passed through the transfer section and The sheet of the fixing device is reverse-conveyed; a first conveying guide is configured to separate a first conveying path from a second conveying path, the first conveying path conveying the sheet from the fixing device toward the discharge member, and the second conveying path conveying the sheet, which has been reverse-conveyed by the reversing member, toward the transfer unit; a fan is configured to generate an airflow; a first air path forming part includes a first opening formed in the first conveying guide, the first air path forming part being configured to guide the airflow through the first opening to the first conveying path; and a second air path forming part includes a second opening formed in the upstream wall, the second air path forming part being configured to guide the airflow from the first conveying path through the second opening to the stacking part.

[0005] The features of this disclosure will become apparent from the following description of embodiments with reference to the accompanying drawings. The following description of the embodiments is by way of example. Attached Figure Description

[0006] Figure 1This is a cross-sectional view of the image forming apparatus according to the first embodiment.

[0007] Figure 2 This is a cross-sectional view showing a portion of the image forming apparatus according to the first embodiment.

[0008] Figure 3 This diagram shows the state in which the opening and closing doors of the image forming apparatus according to the first embodiment are open.

[0009] Figure 4 This is a side view of the image forming apparatus according to the first embodiment.

[0010] Figure 5 This is a diagram showing the opening and closing door according to the first embodiment.

[0011] Figure 6 This is a diagram illustrating the first intermediate guide, the second intermediate guide, and the switching guide according to the first embodiment.

[0012] Figure 7 This is a diagram showing the discharge guide according to the first embodiment.

[0013] Figure 8 This is a perspective view showing the upper part of the image forming apparatus according to the first embodiment.

[0014] Figure 9 This is a schematic diagram showing the arrangement of the blower fan according to the third embodiment.

[0015] Figure 10 This is a schematic diagram showing the arrangement of the blower fan according to the fourth embodiment.

[0016] Figure 11 This is a cross-sectional view showing a portion of the image forming apparatus according to the fifth embodiment.

[0017] Figure 12 This is a cross-sectional view showing a portion of the image forming apparatus according to the sixth embodiment. Detailed Implementation

[0018] Hereinafter, embodiments according to the present disclosure will be described with reference to the accompanying drawings.

[0019] Example 1 Reference Figures 1 to 8 The first embodiment, which is an embodiment of this disclosure, will be described. In terms of the order of description, the overall configuration of the image forming apparatus 1 will be described first, followed by the configuration related to sheet cooling.

[0020] In the following description and figures, the vertical direction (direction of gravity) when the image forming apparatus 1 is mounted on a horizontal plane is defined as the Z-axis direction. The direction of the rotation axis of the photosensitive drum 3 (image carrier member) included in the image forming apparatus 1 is defined as the Y-axis direction. The direction intersecting the Z-axis and Y-axis directions is defined as the X-axis direction. The X-axis, Y-axis, and Z-axis directions are preferably orthogonal to each other.

[0021] As needed, the positive and negative directions along each coordinate axis are represented by a positive (+) or negative (-) sign. For example, the positive direction along the X-axis (the direction shown by arrow X in the figure) is defined as the +X direction, and the negative direction along the X-axis (the side opposite to arrow X) is defined as the -X direction.

[0022] Figure 1 This is a cross-sectional view of the image forming apparatus 1 according to the first embodiment. The image forming apparatus 1 is a monochrome laser printer having the function of forming images on both sides of a sheet S (duplex printing function). However, in this disclosure, "image forming apparatus" is not limited to a monochrome laser printer, and can also be a color laser printer that forms color images using toners of multiple colors. "Image forming apparatus" is not limited to a single-function printer having the function of forming images on a sheet S based on image information received from the outside, and can also be a copier, fax machine, or a multi-functional peripheral device that can copy documents, or has multiple functions such as printer, copier, and fax machine.

[0023] like Figure 1 As shown, the image forming apparatus 1 includes a main frame 1A, an image forming unit 1B, a feeder 30, a fixing device 10 (fixing unit), an ejection unit 20, a reverser 40, and a duplex printing conveyor 50. The image forming unit 1B includes a processing cartridge 2, a scanner unit 4, and a transfer roller 9. The image forming apparatus 1 includes an opening / closing door 80 and a blower fan F. The opening / closing door 80 and the blower fan F are described below.

[0024] The processing box 2 can be attached to and detached from the mounting space in the main frame 1A. When the part of the image forming apparatus 1 other than the processing box 2 is the main body of the image forming apparatus, it can be said that the processing box 2 can be attached to and detached from the main body.

[0025] The processing cartridge 2 includes a photosensitive drum 3, a charging unit 2a, and a developing unit, which includes a developing roller 2b and a developer container 2c. The photosensitive drum 3 functions as an image carrier holding the latent image and the developer image (toner image). The photosensitive drum 3 has a photosensitive layer formed of an organic photosensitive material on the outer periphery of its cylindrical metal base. The charging unit 2a is, for example, a charging roller that contacts the photosensitive drum 3. The toner, as the developer, is stored in the developer container 2c. The developing roller 2b is a developer carrier that holds the toner and supplies it to the facing portions of the developing roller 2b and the photosensitive drum 3.

[0026] The scanning unit 4 is positioned above the processing box 2. The scanner unit 4 includes a laser light source and an optical system that guides the laser emitted from the laser light source to the photosensitive drum 3. The transfer roller 9 is an example of a transfer member that transfers a toner image onto the sheet S. The transfer roller gap, which serves as the transfer section, is formed between the transfer roller 9 and the photosensitive drum 3.

[0027] The term "transfer section" refers to the portion where the toner image is transferred from the image carrier member to the sheet S. In this embodiment, the transfer section is formed between the photosensitive drum 3, which serves as the image carrier member, and the transfer roller 9. However, in an intermediate transfer system, the transfer section is formed between an intermediate transfer member, which serves as the image carrier member, and a secondary transfer member facing the intermediate transfer member. An example of an intermediate transfer member is an intermediate transfer belt, and an example of a secondary transfer member is a secondary transfer roller that contacts the outer surface of the intermediate transfer belt.

[0028] The feeder 30 includes a box 32 (sheet storage section and feed tray) that supports and stores the sheet S, and a feed unit 31. Various sheets of different sizes and materials can be used for the sheet S, which is the recording material (recording medium), such as plain paper or thick paper, surface-treated sheets such as coated paper, sheets with special shapes such as envelope paper or index paper, plastic film, fabric, etc. The box 32 is mounted on the main frame 1A in a pull-out manner. The feed unit 31 includes, for example, a pickup roller located above a lifting plate in the box 32 and a pair of separation rollers disposed downstream of the pickup roller in the sheet feeding direction. The separation roller pair includes a conveying roller and a separation roller in pressure contact with the conveying roller. The separation roller is an example of a separating member that separates the sheet S by applying frictional force to the sheet S at the separation roller gap between the conveying roller and the separation roller.

[0029] The main frame 1A includes frame members (such as metal sheet members) that form the frame of the image forming apparatus 1 and cover members that form the exterior of the image forming apparatus 1. The main frame 1A, together with the opening and closing door 80 described below, forms the generally cuboid exterior surface of the image forming apparatus 1. The main frame 1A and the opening and closing door 80 can be collectively referred to as the housing of the image forming apparatus 1.

[0030] The main frame 1A houses a sheet discharge roller pair 22. The sheet discharge roller pair 22 includes sheet discharge rollers. The Y-axis direction is parallel to the rotation axis of the sheet discharge rollers included in the sheet discharge roller pair 22. A sheet discharge tray 60 is formed on the upper surface of the main frame 1A. The sheet discharge tray 60 is a stacking portion for stacking sheets S discharged by the sheet discharge roller pair 22 along the sheet discharge direction Ds. The sheet discharge direction Ds is a direction intersecting the vertical direction (Z-axis direction). In this embodiment, the sheet discharge direction Ds is a direction intersecting the Z-axis direction and orthogonal to the Y-axis direction, pointing towards the +X direction of the X-axis direction.

[0031] The main frame 1A includes a discharge opening 1D and an upstream wall 61. The upstream wall 61 is disposed upstream of the sheet discharge tray 60 in the sheet discharge direction Ds (first direction) and faces the end (rear edge in the sheet discharge direction Ds) of the sheet S stacked on the sheet discharge tray 60. The upstream wall 61 extends in the Z-axis direction below the discharge opening 1D and above the upstream end of the sheet discharge tray 60 in the sheet discharge direction Ds. The discharge opening 1D is an opening through which the sheet S discharged from the inside to the outside of the housing by the discharge roller pair 22 passes. The discharge opening 1D is formed above the upstream wall 61.

[0032] The fixing device 10 is housed within the main frame 1A. That is, the fixing device 10 is housed within the housing of the image forming apparatus 1. The fixing device 10 heats the toner image on the sheet S to fix the toner image onto the sheet S.

[0033] The fixing device 10 in this embodiment is a film heating type device, which includes a film 11 as a fixing component and a heater 13 for heating the film 11. Figure 2 A pressure roller 12 contacts the outer surface of the membrane 11. The membrane 11 is a tubular member formed of a flexible resin sheet, a metal sheet, or a composite material sheet. A heater 13 is disposed within the internal space of the membrane 11. For example, a ceramic heater can be used as the heater 13, wherein a pattern of a heating resistor that generates heat when energized is printed on a ceramic substrate. The heater 13 is held by a heater holder, which is held by a metal support serving as a reinforcing member. When the metal support is biased toward the pressure roller 12 by a spring member (not shown), the heater 13 and the heater holder are in pressure contact with the pressure roller 12, with the membrane 11 situated between them. Thus, a fixing roller gap is formed between the membrane 11 and the pressure roller 12.

[0034] Here, a film-heated fixing device 10 has been exemplified, but the configuration of the fixing device 10 is not limited to this. For example, as the fixing member, a rigid cylindrical roller member can be used, or a belt member stretched around multiple rollers can be used. As the heating unit, a halogen lamp that generates radiant heat when energized or a coil that generates heat in the fixing member itself through induction heating can be used.

[0035] The discharge unit 20 includes an intermediate transport roller pair 21, a sheet discharge roller pair 22, and a full-load detection sensor 23. The sheet discharge roller pair 22 is an example of a discharge member that discharges a sheet S with a toner image fixed by the fixing device 10 from the inside to the outside of the housing of the image forming apparatus 1 along the sheet discharge direction Ds. The intermediate transport roller pair 21 is disposed between the fixing device 10 and the sheet discharge roller pair 22 in the sheet transport direction from the fixing device 10 toward the sheet discharge roller pair 22. The full-load detection sensor 23 includes: a marker configured to pivot by being pressed against the sheet S discharged by the sheet discharge roller pair 22 toward the sheet discharge tray 60; and a detection unit (e.g., a light blocker) that detects the pivoting of the marker.

[0036] The reverser 40 includes a reverse transport roller pair 42 and a switching guide 41. The reverse transport roller pair 42 is an example of a reverse member that reverses the transport of the sheet material passing through the transfer roller gap (transfer section) and the fixing device 10. The reverse transport roller pair 42 reverses the transport of the sheet material S having the first side with the image formed, when images are formed on both sides of the sheet material S. The reverse transport roller pair 42 is configured to rotate in the reverse direction so that after transporting the sheet material S along the first transport direction U (upper direction in the figure), a reverse transport operation (foldback operation) is performed to transport the sheet material S along the second transport direction D opposite to the first transport direction U. The main frame 1A has a reverse opening 1R, which allows a portion of the sheet material S to protrude to the outside of the image forming apparatus 1 during the reverse transport operation.

[0037] The switching guide 41 is a sheet-like guide member that switches the conveying path of the sheet S. The switching guide 41 is capable of guiding the sheet S to the discharge position (corresponding to) the first conveying path 101 described below. Figure 1 The first position and the first posture of the solid line position in the image) and the reverse position for guiding the sheet S to the second conveying path 102 (corresponding to the first position and the first posture ... Figure 2 It moves between the second position and the second pose (the position indicated by the dotted line in the diagram).

[0038] The double-sided printing conveyor 50 includes a double-sided printing conveyor roller pair 51 and a refeed roller pair 52. The double-sided printing conveyor roller pair 51 and the refeed roller pair 52 are configured to convey (refeed) the sheet S reversed by the reverse conveyor roller pair 42 to the image forming unit 1B again.

[0039] Image forming operations The image forming operation, a series of operations performed by the image forming apparatus 1 to form an image on the sheet S while it is being fed, will be described. The control unit of the image forming apparatus 1 performs the image forming operation, for example, when it receives image information and an image forming instruction (print signal) from an external source.

[0040] When the image formation operation begins, the photosensitive drum 3 is driven by a motor and begins to rotate, and the charging unit 2a uniformly charges the surface of the photosensitive drum 3. The control unit generates a video signal based on the received image information. The scanning unit 4 is driven according to the video signal and exposes the photosensitive drum 3, thereby writing an electrostatic latent image corresponding to the image information onto the surface of the photosensitive drum 3. The electrostatic latent image is developed into a toner image by the toner supplied to the photosensitive drum 3 by the developing roller 2b.

[0041] Furthermore, the sheets S stored in the cartridge 32 are supplied one by one by the supply unit 31 driven by the supply motor. The supplied sheets S are conveyed to the registration roller pair 8 via the transport roller pair 73, and skew supply correction is performed by the registration roller pair 8. The registration roller pair 8 conveys the sheets S to the transfer roller gap according to the time when the toner image formed on the photosensitive drum 3 arrives at the transfer roller gap.

[0042] A positive transfer voltage is applied to the transfer roller 9 at the transfer roller gap, causing the toner image to be transferred from the photosensitive drum 3 to the sheet S. The sheet S, having passed through the transfer roller gap, is conveyed to the fixing device 10 for image fixing. The fixing device 10 heats and presses the toner image on the sheet S while rolling and conveying it at the fixing roller gap.

[0043] In the case of single-sided printing where an image is formed on one side of the sheet S, the switching guide 41 waits for the sheet S at the discharge position (solid line position). The sheet S, having passed through the fixing device 10, is guided by the switching guide 41 at the discharge position to the first transport path 101. The sheet S, guided to the first transport path 101, is transported towards the sheet discharge roller pair 22 via the intermediate transport roller pair 21. Then, the sheet S is discharged by the discharge roller pair 22 to the outside of the image forming apparatus 1 and stacked on the sheet discharge tray 60.

[0044] As the sheet S is discharged from the inside to the outside of the image forming apparatus 1, the sheet S contacts the mark of the full load detection sensor 23 and raises the mark. As the amount of sheet stacked on the sheet discharge tray 60 increases, the mark of the full load detection sensor 23 is continuously raised by the upper surface of the sheet stack. When the full load detection sensor 23 continuously detects the presence of sheet S, the control unit of the image forming apparatus 1 determines that the sheet discharge tray 60 is full.

[0045] On the other hand, in the case of double-sided printing where images are formed on both sides of the sheet S, the switching guide 41 waits in the reverse position (dashed line position). The sheet S, after passing through the fixing device 10, is guided by the switching guide 41 in the reverse position to the second transport path 102. The reverse transport roller pair 42 performs the following reverse transport operation on the sheet S. The reverse transport roller pair 42 transports the sheet S towards the reverse opening 1R along the first transport direction U (upper direction in the figure), and then rotates in the reverse direction after the trailing edge of the sheet S passes the switching guide 41 and before the trailing edge of the sheet S passes the reverse transport roller pair 42, so as to transport the sheet S along the second transport direction D.

[0046] When the trailing edge of sheet S passes the switching guide 41, the switching guide 41 returns to... Figure 1 The solid line position in the diagram. Therefore, it prevents the sheet S, which is reversed by the reverse conveyor roller pair 42, from moving back to the first conveyor path 101.

[0047] Subsequently, in the same process as single-sided printing, an image is formed on the back side of the sheet S, which is reversed by the reverse conveyor roller pair 42. That is, the sheet S conveyed from the refeed roller pair 52 undergoes sequential skew supply correction by the registration roller pair 8, transfer of the toner image at the transfer roller gap, and image fixing processing by the fixing device 10. After images are formed on both sides of the sheet S, the sheet S is guided to the first conveyor path by the switching guide 41. Then, with images formed on the first and second sides, the sheet S is discharged into the sheet discharge tray 60.

[0048] Sheet conveying path Next, we will refer to Figure 1 and Figure 2 The structure of the sheet transport path located downstream of the fixing device 10 is described. Figure 2 yes Figure 1 An enlarged view of a portion of the image forming apparatus 1. Figure 1 and Figure 2 This is a diagram of the image forming apparatus 1 when viewed in the Y-axis direction.

[0049] In the image forming apparatus 1, a sheet transport path (transport path) is formed, which is a transport space connecting the box 32 to the sheet discharge tray 60. In this embodiment, the sheet transport path includes a first transport path 101 and a second transport path 102.

[0050] The first transport path 101 is a transport path (discharge path) that transports the sheet S from the fixing device 10 toward the sheet discharge roller pair 22. The second transport path 102 is a transport path (reverse path and double-sided printing path) that transports the sheet S, which has been reverse-transported by the reverse transport roller pair 42, toward the transfer roller gap (transfer section) again. In this embodiment, the second transport path 102 includes a path from the reverse transport roller pair 42 via the double-sided printing transport roller pair 51 and the refeed roller pair 52 to the registration roller pair 8. The second transport path 102 includes a space from the reverse transport roller pair 42 to the reverse opening 1R. The second transport path 102 can also be referred to as a transport path that branches off from the cartridge 32 via the transfer roller gap and the fixing roller gap to the sheet discharge tray 60 at a position downstream of the fixing roller gap, and connects to the image forming path at a position upstream of the registration roller pair 8.

[0051] The switching guide 41 is disposed in the connecting portion (connecting part) where the first conveying path 101 and the second conveying path 102 communicate with each other. The discharge position (solid line position) of the switching guide 41 can be described as the position where the switching guide 41 closes the connecting portion to restrict the sheet S from moving from one of the first conveying path 101 to the other. The reverse position (dashed line position) of the switching guide 41 can be described as the position where the switching guide 41 closes the first conveying path 101 and opens the connecting portion.

[0052] The image forming apparatus 1 includes a discharge guide 86, a first intermediate guide 65, a second intermediate guide 66, a first reverse guide 81, and a second reverse guide 82.

[0053] Each of the first intermediate guide 65 and the second intermediate guide 66 is an example of a first conveying guide forming the first conveying path 101. Each of the first reverse guide 81 and the second reverse guide 82 is an example of a second conveying guide disposed on the side opposite to the first conveying guide relative to the second conveying path 102. The discharge guide 86 is an example of a third conveying guide disposed on the side opposite to the first conveying guide relative to the first conveying path 101.

[0054] The discharge guide 86 is disposed on one side of the first transport path 101, and the first intermediate guide 65 and the second intermediate guide 66 are disposed on the other side of the first transport path 101. That is, the discharge guide 86 is disposed facing the first side of the sheet S transported through the first transport path 101. The first intermediate guide 65 and the second intermediate guide 66 are disposed facing a second side opposite to the first side of the sheet S transported through the first transport path 101. Here, the distinction between the first side and the second side is merely for convenience and does not need to be consistent with, for example, the image formation order during double-sided printing.

[0055] The first reverse guide 81 and the second reverse guide 82 are disposed on one side of the second conveying path 102, and the first intermediate guide 65 and the second intermediate guide 66 are disposed on the other side of the second conveying path 102. That is, the first reverse guide 81 and the second reverse guide 82 are configured to face the first side of the sheet S conveyed through the second conveying path 102. The first intermediate guide 65 and the second intermediate guide 66 are configured to face a second side opposite to the first side of the sheet S conveyed through the second conveying path 102. Here, the distinction between the first side and the second side is merely for convenience.

[0056] The first intermediate guide 65 and the second intermediate guide 66 are configured such that the first conveying path 101 and the second conveying path 102 are separated from each other. That is, the first intermediate guide 65 and the second intermediate guide 66 are positioned between two conveying paths (101 and 102) that extend in the direction along the Z-axis when viewed along the Y-axis and are arranged in the direction along the X-axis.

[0057] The second intermediate guide 66 is disposed above the first intermediate guide 65. That is, the second intermediate guide 66 is disposed downstream of the first intermediate guide 65 in the first conveying path 101 in the sheet conveying direction from the fixing device 10 toward the sheet discharge roller pair 22 (and the first conveying direction U of the reverse conveying roller pair 42).

[0058] The first intermediate guide 65 includes a discharge-side guide 65a, and the second intermediate guide 66 includes a discharge-side guide 66a, the discharge-side guides 65a and 66a forming at least a portion of the wall of the first conveying path 101 (see also...). Figure 3 The first intermediate guide 65 includes a reverse-side guide 65b, and the second intermediate guide 66 includes a reverse-side guide 66b, the reverse-side guides 65b and 66b forming at least a portion of the wall of the second conveying path 102 (see also...). Figure 3 and Figure 6 When at least one of the first intermediate guide 65 and the second intermediate guide 66 is referred to as the first conveying guide, the discharge side guides 65a and 66a are the first side of the first conveying guide, and the reverse side guides 65b and 66b are the second side of the first conveying guide.

[0059] Discharge guide 86 includes guide portion 86a, which forms at least a portion of the wall of the first conveying path 101 (see also...) Figure 3 and Figure 7 The first reverse guide 81 includes a guide portion 81a, and the second reverse guide 82 includes a guide portion 82a, the guide portions 81a and 82a forming at least a portion of the wall of the second conveying path 102 (see also...). Figure 3 and Figure 5 ).

[0060] In this embodiment, the discharge-side guide portions 65a and 66a of the first intermediate guide 65 and the second intermediate guide 66 face the guide portion 86a of the discharge guide 86. For example, when viewed in the X-axis direction, the discharge-side guide portion 65a of the first intermediate guide 65 overlaps with the guide portion 86a of the discharge guide 86, and the discharge-side guide portion 66a of the second intermediate guide 66 overlaps with the guide portion 86a of the discharge guide 86.

[0061] Here, the fact that two elements overlap when viewed in a specific direction means that when the corresponding elements are projected perpendicularly onto a virtual plane perpendicular to the specific direction, the projection areas of one element and the projection areas of the other element at least partially overlap.

[0062] In this embodiment, the reverse-side guide portions 65b and 66b of the first intermediate guide 65 and the second intermediate guide 66 face the guide portion 82 of the second reverse guide 82. Furthermore, the reverse-side guide portion 65b of the first intermediate guide 65 faces the guide portion 81a of the first reverse guide 81. For example, when viewed in the X-axis direction, the reverse-side guide portion 65b of the first intermediate guide 65 overlaps with the guide portion 82 of the second reverse guide 82, and the reverse-side guide portion 66b of the second intermediate guide 66 overlaps with the guide portion 82 of the second reverse guide 82. Furthermore, for example, when viewed in the X-axis direction, the reverse-side guide portion 65b of the first intermediate guide 65 overlaps with the guide portion 81a of the first reverse guide 81.

[0063] Ribs for enhancing sliding relative to sheet S can be formed in the discharge guide 86, the first intermediate guide 65, the second intermediate guide 66, the first reverse guide 81, and the second reverse guide 82. Figures 5 to 7 At each guide portion in the sheet, the ribs are multiple protrusions arranged side by side in the X-axis direction, which is the width direction of the sheet, and extending in the sheet conveying direction. Each guide portion is provided with an opening that forms a flow path (air path) for the cooling air described below.

[0064] Opening and closing doors Reference Figure 1 and Figure 3 The opening and closing gate 80 of the image forming apparatus 1 is described. Figure 3 This is a cross-sectional view of the image forming apparatus 1 showing the state of the open / closed door 80. Figure 3 This is a diagram of the image forming apparatus 1 when viewed in the Y-axis direction.

[0065] Door 80 is an opening and closing unit (door unit), which can be in the closed position ( Figure 1) and open location ( Figure 3 The opening / closing door 80 moves between the two positions. In the closed position, the opening / closing door 80 closes the back opening 1J, which is an opening formed in the main frame 1A. In the open position, the opening / closing door 80 opens the back opening 1J. The back opening 1J is formed at the end of the main frame 1A in the direction opposite to the sheet discharge direction Ds (first direction). When the opening / closing door 80 is in the closed position, the opening / closing door 80 is pivotally supported by the main frame 1A around a pivot axis 80p located at the lower end of the opening / closing door 80.

[0066] like Figure 3 As shown, the first reverse guide 81 and the second reverse guide 82 are included in the opening / closing door 80. The discharge guide 86, the first intermediate guide 65, the second intermediate guide 66, the switching guide 41, etc., are included in the main frame 1A. When the opening / closing door 80 moves from the closed position to the open position, the first reverse guide 81 and the second reverse guide 82 move away from the first intermediate guide 65, the second intermediate guide 66, and the switching guide 41. That is, when the opening / closing door 80 is opened, the back opening 1J is opened, exposing at least a portion of the second transport path 102 to the outside of the image forming apparatus 1. Therefore, in the event of a jam (paper jam) where the sheet S is stuck in the second transport path 102, the user can open the opening / closing door 80, enter the second transport path 102, and remove the jammed sheet S.

[0067] Additionally, an interlocking mechanism is provided that, in conjunction with the operation of moving the opening / closing door 80 from the closed position to the open position, moves the switching guide 41 from the discharge position or the reverse position to the position indicated by the alternating long and short dashed lines in the accompanying drawings (retracted position). For example, when the switching guide 41 is in the retracted position, the connection between the first transport path 101 and the second transport path 102 is exposed when viewed from the outside of the image forming apparatus 1 along the X-axis. Therefore, for example, if a jam (paper jam) occurs in the first transport path 101 where the sheet S is stuck between the fixing device 10 and the intermediate transport roller pair 21, the user can open the opening / closing door 80, enter the first transport path 101, and remove the jammed sheet S.

[0068] Additionally, an interlocking mechanism is provided that, in conjunction with the operation of moving the opening / closing door 80 from the closed position to the open position, moves the second intermediate guide 66 from the position during image formation (solid line position) to the position indicated by the lines in the accompanying drawings with alternating long and short dashed lines (retracted position). For example, when the second intermediate guide 66 is in the retracted position, when viewed from the outside of the image forming apparatus 1 along the X-axis direction, a portion of the first transport path 101 is exposed above the intermediate transport roller pair 21. Therefore, for example, if a jam (paper jam) occurs in the first transport path 101 where the sheet S is stuck between the intermediate transport roller pair 21 and the sheet discharge roller pair 22, the user can open the opening / closing door 80, enter the first transport path 101, and remove the jammed sheet S.

[0069] The interlocking mechanism that moves the switching guide 41 or the second intermediate guide 66 together with the opening / closing door 80 to the retracted position can be omitted, and the user can manually move the switching guide 41 or the second intermediate guide 66 to the retracted position. For example, when the conveying distance from the fixing device 10 to the sheet discharge roller pair 22 is short, the switching guide 41 and the second intermediate guide 66 do not need to be moved to the retracted position. In this case, the sheet S stuck in the first conveying path 101 can be removed, for example, by the user pulling the leading edge of the sheet S protruding from the sheet discharge roller pair 22, or by being pulled out to an upstream position of the fixing device 10 when the processing cartridge 2 has been removed.

[0070] Cooling components of the transport path Next, we will refer to Figure 2 and Figures 4 to 8 The configuration for cooling the first conveying path 101, the second conveying path 102, and the sheet S passing through the first conveying path 101 and the second conveying path 102 is described. Figure 2 It is a cross-sectional view of the image forming apparatus 1 taken along a virtual plane extending in the Z-axis and X-axis directions, and shows openings, etc., as flow paths for cooling air. Figure 4 From Figure 1 The side view of the image forming apparatus 1 when viewed along the X-axis from the left. Figure 5 It is a 3D diagram of the opening and closing door 80. Figure 6 This is a diagram showing the image forming apparatus 1 with the door 80 open when viewed in the X-axis direction. Figure 7 This is a diagram showing the discharge guide 86 and discharge roller pair 22 when viewed from the inside of the image forming apparatus 1 along the X-axis direction. Figure 8 This is a perspective view showing the upper part of the image forming apparatus 1.

[0071] like Figure 2 and Figure 3As shown, the image forming apparatus 1 includes a blower fan F (fan) as a blower unit that generates airflow. In this embodiment, the blower fan F is installed inside the opening / closing door 80.

[0072] As described below, the blower fan F draws in air from the outside of the image forming apparatus 1 through the air inlet 80s to generate an airflow (cooling air). The airflow generated by the blower fan F passes sequentially through the inner air outlet 82s, the second conveying path 102, the first air vents 65s and 66s, the first conveying path 101, the second air vent 86s, and the outer air outlet 61s, and is blown onto the sheet S on the sheet discharge tray 60.

[0073] Each of the first vents 65s and 66s is an example of a first opening formed in the first intermediate guide 65 or the second intermediate guide 66, which serves as the first conveying guide. The external air outlet 61s is an example of a second opening formed in the upstream wall 61. The internal air outlet 82s is an example of a third opening formed in the second reverse guide 82, which serves as the second conveying guide. The second vent 86s is an example of a fourth opening formed in the discharge guide 86, which serves as the third conveying guide. Figure 2 In the middle, the arrows extending in the vertical direction and indicating the first vent 65s and 66s, the external air outlet 61s, the internal air outlet 82s and the second vent 86s respectively indicate the opening range of the first vent 65s and 66s, the external air outlet 61s, the internal air outlet 82s and the second vent 86s in the vertical direction.

[0074] In the image forming apparatus 1, the portion that guides the airflow generated by the blower fan F from the blower fan F to the first conveying path 101 can be referred to as the first air path forming section 120, and the portion that guides the airflow from the first conveying path 101 to the sheet discharge tray 60 can be referred to as the second air path forming section 121.

[0075] The first air path forming section 120 in this embodiment includes an internal air outlet 82s, a portion of the second conveying path 102, and first vents 65s and 66s. The second air path forming section 121 in this embodiment includes a second vent 86s and an external air outlet 61s. That is, the first air path forming section 120 in this embodiment is configured to guide airflow from the blower fan F to the first conveying path 101 via the first vents 65s and 66s, which are first openings. The second air path forming section 121 in this embodiment is configured to guide airflow from the first conveying path 101 to the sheet discharge tray 60 via the external air outlet 61s, which is a second opening.

[0076] like Figure 2 and Figure 4As shown, an air inlet 80s is formed in a cover member 80a that forms the outer surface of the opening and closing door 80. The air inlet 80s is an opening through which air entering the image forming apparatus 1 from the outside passes during the rotation of the blower fan F. The air inlet 80s is located on the outer surface side of the blower fan F.

[0077] An air inlet 80s is formed on the end face of the opening / closing door 80 facing the direction opposite to the sheet discharge direction Ds (the -X direction of the X-axis). The air inlet 80s is formed in the cover member 80a at a position facing the blower fan F in the X-axis direction. That is, the blower fan F is positioned between the air inlet 80s and the second conveying path 102 in the sheet discharge direction Ds. In the example shown, the air inlet 80s is formed by a plurality of regularly arranged circular holes 80s1, but the shape, number, and position of the openings (holes) forming the air inlet 80s can be changed.

[0078] like Figure 2 and Figure 5 As shown, an internal air outlet 82s is formed in the second reverse guide 82. The internal air outlet 82s is an opening (third opening) through which air is discharged from the blower fan F toward the second conveying path 102. The internal air outlet 82s extends from the guide portion 82a of the second reverse guide 82 to the surface opposite to the guide portion 82a (the surface facing the blower fan F in the X-axis direction). The internal air outlet 82s is located on the side opposite to the air inlet 80s relative to the blower fan F. The internal air outlet 82s faces the blower fan F in the X-axis direction.

[0079] The internal air outlet 82s of this embodiment includes a plurality of elongated holes 82s1 arranged along the Y-axis direction. Each elongated hole 82s1 is formed between adjacent ribs formed in the guide portion 82a of the second reverse guide 82, and is elongated in the Z-axis direction. The shape, number, position, etc. of the openings (holes) forming the internal air outlet 82s are not limited to this, and can be changed.

[0080] like Figure 2 and Figure 6 As shown, first vents 65s and 66s are formed in the first intermediate guide 65 and the second intermediate guide 66. The first vents 65s and 66s are openings forming a channel (first opening) through which air flows from the second conveying path 102 to the first conveying path 101. The first vents 65s and 66s extend from the reverse side guides 65b and 66b to the discharge side guides 65a and 66a.

[0081] The first vents 65s and 66s in this embodiment include a plurality of elongated holes 65s1 and 66s1 arranged along the Y-axis direction. When viewed in the X-axis direction, each of the elongated holes 65s1 and 66s1 is formed at a position that does not overlap with the ribs formed in the reverse side guides 65b and 66b and the discharge side guides 65a and 66a, and is elongated in the Z-axis direction. The shape, number, position, etc. of the openings (holes) forming the first vents 65s and 66s are not limited thereto and can be changed. In this embodiment, the first vents 65s and 66s are formed in both the first intermediate guide 65 and the second intermediate guide 66, but the first vents 65s or 66s may be formed in only one of the first intermediate guide 65 and the second intermediate guide 66.

[0082] like Figure 2 and Figure 7 As shown, a second vent 86s is formed in the discharge guide 86. The second vent 86s is an opening (fourth opening) for receiving air from the first transport path 101. The second vent 86s extends from the guide portion 86a of the discharge guide 86 to the surface opposite to the guide portion 86a.

[0083] The second vent 86s of this embodiment includes a plurality of elongated holes 86s1 arranged along the Y-axis direction. Each elongated hole 86s1 is formed between adjacent ribs formed in the guide portion 86a of the discharge guide 86, and is elongated in the Z-axis direction. The shape, number, position, etc. of the openings (holes) forming the second vent 86s are not limited thereto, and can be changed.

[0084] like Figure 2 and Figure 8 As shown, an external air outlet 61s is formed in the upstream wall 61 of the main frame 1A. The external air outlet 61s is an opening (the second opening) through which air received from the first conveying path 101 by the second vent 86s is blown into the space above the sheet discharge tray 60. The external air outlet 61s extends from the outer surface of the upstream wall 61 to its inner surface. The outer surface of the upstream wall 61 is the surface facing the outside of the image forming apparatus 1. Figure 2 The surface on the right side of the upstream wall 61), the inner surface of the upstream wall 61 is the surface facing the inside of the image forming apparatus 1 ( Figure 2 (The left side surface of the upstream wall 61 in the middle).

[0085] The external air outlet 61s of this embodiment includes a plurality of elongated holes 61s1 arranged along the Y-axis direction. Each elongated hole 61s1 is formed between adjacent sheet edge receiving portions 62 (described below) and is elongated in the Z-axis direction. The shape, number, position, etc. of the openings (holes) forming the external air outlet 61s are not limited thereto and can be changed.

[0086] In this embodiment, as Figure 2 As shown, the air inlet 80s, blower fan F, internal air outlet 82s, first air vents 65s and 66s, second air vent 86s, and external air outlet 61s are arranged sequentially in the +X direction of the horizontal direction. In other words, when viewed in the Y-axis direction (including the direction of the rotation axis of the discharge rollers in the sheet discharge roller pair 22), the air inlet 80s, blower fan F, internal air outlet 82s, first air vents 65s and 66s, second air vent 86s, and external air outlet 61s are arranged sequentially in the +X direction. Alternatively, it can be said that the air inlet 80s, blower fan F, internal air outlet 82s, first air vents 65s and 66s, second air vent 86s, and external air outlet 61s are arranged sequentially from upstream to downstream of the sheet discharge direction Ds in the horizontal direction. Therefore, the airflow direction can be aligned, and the airflow can be guided more smoothly.

[0087] like Figure 2 As shown, preferably, the opening range of the air inlet 80s and the opening range of the internal air outlet 82s overlap with each other in the vertical direction (Z-axis direction). The vertical overlap of the opening range of one opening (the first opening) with the opening range of another opening (the second opening) means that the range from the upper end to the lower end of the first opening and the range from the upper end to the lower end of the second opening at least partially overlap each other in the Z-axis. In other words, the vertical overlap of the opening range of one opening (the first opening) with the opening range of another opening (the second opening) means that at least a portion of the first opening and at least a portion of the second opening are in the same position in the vertical direction.

[0088] Preferably, the opening range of the internal air outlet 82s (the third opening) and the opening range of the first vents 65s and 66s (the first opening) overlap with each other in the vertical direction (Z-axis direction). Preferably, the opening range of the first vents 65s and 66s (the first opening) and the opening range of the second vent 86s (the fourth opening) overlap with each other in the vertical direction (Z-axis direction). Preferably, the opening range of the second vent 86s (the fourth opening) and the opening range of the external air outlet 61s (the second opening) overlap with each other in the vertical direction (Z-axis direction).

[0089] As described above, the openings are arranged such that the opening ranges of adjacent openings in the vertical direction overlap each other in the direction of airflow, thereby facilitating airflow. The openings can be arranged such that, when viewed in the X-axis direction, adjacent openings overlap each other in the direction of airflow.

[0090] like Figures 4 to 7As shown, each of the internal air outlet 82s, the first air vents 65s and 66s, the second air vent 86s, and the external air outlet 61s can preferably be formed symmetrically with respect to the conveying center Y0, which is the center of the conveying path in the Y-axis direction (sheet width direction). The conveying center Y0 is a reference for the position of the sheet S conveyed during image formation in the Y-axis direction. To avoid skewed feeding of the sheet S, the contact surfaces of the conveying roller pairs, such as the sheet discharge roller pair 22 and the reverse conveying roller pair 42, that contact the sheet S are symmetrically arranged with respect to the conveying center Y0.

[0091] Since the internal air outlet 82s, the first air outlets 65s and 66s, the second air outlet 86s and the external air outlet 61s are formed symmetrically with respect to the conveying center Y0, the sheet S, the first conveying path 101 and the second conveying path 102 can be cooled in a balanced manner along the Y-axis direction.

[0092] The airflow during the transport of sheet S (during the image forming operation) and the advantages of this embodiment compared to the comparative example will be described below.

[0093] In the following text, the operation of printing on one side of each sheet S while continuously feeding multiple sheets S is called continuous single-sided printing. The operation of printing on both sides of each sheet S while continuously feeding multiple sheets S is called continuous double-sided printing. Continuous single-sided printing and continuous double-sided printing can be simply referred to as "continuous printing". In continuous printing, the interval from passing the trailing edge of the previous sheet to passing the leading edge of the next sheet in two consecutively fed sheets S in a specific section of the sheet feed path is called the sheet gap or paper gap.

[0094] Cooling of the sheet during continuous printing During continuous printing, the air discharged from the first vents 65s and 66s cools the sheet S passing through the first conveying path 101. When the sheet S does not pass through the first conveying path 101, the air discharged from the first vents 65s and 66s passes directly through the first conveying path 101, enters the second vent 86s, and is discharged from the external air outlet 61s. The air discharged from the external air outlet 61s primarily cools the top sheet S of the stack of sheets piled on the sheet discharge tray 60.

[0095] Even if sheet S passes through the first conveying path 101, a portion of the air discharged from the first vent 65s and 66s also bypasses sheet S or passes through sheet S to enter the second vent 86s.

[0096] As a first comparative example relative to this embodiment, a configuration in which air from the blower fan F cools the sheet S on the sheet discharge tray 60 without passing through the first transport path 101 will be considered. However, in the configuration of the comparative example, especially when the sheet interval is short during continuous printing, there is a possibility that the cooling of the sheet S on the sheet discharge tray 60 may become insufficient. In the case of insufficient cooling of the sheet S on the sheet discharge tray 60, heat is confined within the stacked sheet stack, and the toner on the sheet S softens during fixing and then softens again, which may cause adhesion between the sheets S.

[0097] Specifically, the shorter the sheet interval in continuous printing, the shorter the time from when a sheet S is discharged onto the sheet discharge tray 60 until the next discharged sheet S overlaps with another sheet S. In other words, when focusing on any sheet S in continuous printing except the last sheet S, the time that sheet S corresponds to the top sheet on the sheet discharge tray 60 (i.e., the time that air from the blower fan F is applied to sheet S) is shortened. Therefore, in the first comparative example, the shorter the sheet interval in continuous printing, the shorter the time that air from the blower fan F is applied to each sheet, and thus the cooling of sheet S tends to be insufficient.

[0098] According to this embodiment, air from the blower fan F is applied to the sheet S passing through the first transport path 101. Therefore, even when the sheet interval is shortened during continuous printing, air from the blower fan F is applied to the sheet S at least during the period when the sheet S passes the position facing the first vent 65s and 66s in the first transport path 101. Furthermore, similar to the first comparative example, during the period when the sheet S is discharged to the sheet discharge tray 60 corresponding to the uppermost sheet, the sheet S is cooled by air discharged from the external air outlet 61s.

[0099] As described above, according to this embodiment, the sheet S can be cooled when it passes through the first transport path 101 and when it corresponds to the topmost sheet on the sheet discharge tray 60. Therefore, the sheet S can be sufficiently cooled. Furthermore, by shortening the sheet interval in continuous printing, the sheet S can be sufficiently cooled while improving the productivity of the image forming apparatus 1.

[0100] As described above, according to this embodiment, an image forming apparatus capable of adequately cooling the sheet can be provided.

[0101] Cooling of the sheet during continuous duplex printing Next, the airflow in continuous duplex printing will be described. In continuous duplex printing, air discharged from the inner air outlet 82s cools the sheet S passing through the second transport path 102. When the sheet S does not pass through the second transport path 102, the air discharged from the inner air outlet 82s passes directly through the second transport path 102, enters the first vents 65s and 66s, and is discharged to the first transport path 101. The air discharged from the first vents 65s and 66s to the first transport path 101 cools the sheet S passing through the first transport path 101. When the sheet S does not pass through the first transport path 101, the air discharged from the first vents 65s and 66s passes directly through the first transport path 101, enters the second vent 86s, and is discharged from the outer air outlet 61s. The air discharged from the outer air outlet 61s primarily cools the top sheet S of the stack of sheets piled on the sheet discharge tray 60.

[0102] By cooling the sheet S passing through the second conveying path 102, the temperature rise of the components disposed in and around the second conveying path 102 can be suppressed, and the deformation of components with low heat resistance can be suppressed.

[0103] According to this embodiment, the sheet S conveyed through the second conveyor path 102 can be further cooled by a blower fan F that generates air to cool the sheet S in the first conveyor path 101 and the sheet S in the sheet discharge tray 60. Therefore, the second conveyor path 102 can be cooled with a simple configuration.

[0104] Specifically, in this embodiment, the internal air outlet 82s is located downstream of the reverse conveying roller pair 42 in the first conveying direction U. Then, midway through the reverse conveying operation, after the sheet S is cooled by the air discharged from the internal air outlet 82s, the sheet S is conveyed from the reverse conveying roller pair 42 toward the registration roller pair 8. Therefore, for example, compared to the configuration where air for cooling the sheet S is applied between the reverse conveying roller pair 42 and the registration roller pair 8 in the second conveying path 102, the sheet S can be cooled at an earlier time, and the area affected by heat can be reduced.

[0105] Sliding friction with the conveyor guide like Figure 2 As shown, when viewed in the Y-axis direction, the gap line L22 of the sheet discharge roller pair 22 intersects the gap line L21 of the intermediate conveyor roller pair 21 at an oblique angle. The angle between the gap lines L21 and L22 is α. α can be, for example, more than 90° and less than 150°, and can also be less than 135°. That is, the direction of movement of the sheet S at the gap of the sheet discharge roller pair 22 (along the direction of the gap line L22) is different from the direction of movement of the sheet S at the gap of the intermediate conveyor roller pair 21 (along the direction of the gap line L21).

[0106] When the sheet S is bent between the intermediate conveying roller pair 21 and the sheet discharge roller pair 22, the second intermediate guide 66, which is the first conveying guide, is located outside the bent portion of the sheet S.

[0107] Because the direction of movement of the sheet S differs between the sheet discharge roller pair 22 and the intermediate conveyor roller pair 21, which is adjacent to and upstream of the sheet discharge roller pair 22, the trailing edge of the sheet S can slide against the conveyor guide 24 after passing the intermediate conveyor roller pair 21. That is, when the trailing edge of the sheet S passes the intermediate conveyor roller pair 21, due to the rigidity of the sheet S itself, the posture of the sheet S tends to straighten along the nip line L22 of the sheet discharge roller pair 22. At this time, there is a possibility that the trailing edge of the sheet S moves to approach the second intermediate guide 66 and slides against the discharge side guide 66a of the second intermediate guide 66. In the case of double-sided printing, the sheet surface on which the image has been transferred during the first transfer (hereinafter referred to as the first printing surface) slides against the discharge side guide 66a, thereby peeling off the toner, and the discharge side guide 66a may be contaminated by the toner, or interference with the image on the image sheet S may occur.

[0108] According to this embodiment, at least a portion of the first vents 65s and 66s (first openings) are located upstream of the intermediate conveyor roller pair 21 in the first conveying path 101. Therefore, in double-sided printing, the first printed surface of the sheet S can be cooled before the trailing edge of the sheet S passes the intermediate conveyor roller pair 21, and the contamination of the discharge side guide 66a by toner and interference with the image on the first printed surface of the sheet S can be suppressed.

[0109] Location of external air outlet In this embodiment, the lower end 61sD of the external air outlet 61s ( Figure 2 It can be connected to the lower end 61D of the upstream wall 61 (see also...) Figure 8 The lower end of the second opening can be at the same height as the upper surface of the sheet discharge tray 60 (stacked portion) at the upstream end of the sheet discharge tray 60 in the sheet discharge direction Ds (first direction). For example, a groove with an opening at the lower end can be formed in the upstream wall 61, and an external air outlet 61s can be formed by inserting an upward surface 60b, which is continuous with the stacked surface 60a of the sheet discharge tray 60, into the groove (see also...). Figure 8 Since the lower end 61sD of the external air outlet 61s is at the same height as the lower end 61D of the upstream wall 61, the sheets S on the sheet discharge tray 60 can be effectively cooled even when the number of sheets S stacked on the sheet discharge tray 60 is small (e.g., one sheet S stacked).

[0110] Blower fan arrangement In this embodiment, the blower fan F is positioned above the reverse conveyor roller pair 42 so that it overlaps with the reverse conveyor roller pair 42 when viewed in the Z-axis direction. Figure 2 In other words, the reverse conveying roller pair 42 and the blower fan F are positioned differently in the Z-axis direction, and the areas occupied by the reverse conveying roller pair 42 and the blower fan F in the X-axis direction at least partially overlap each other.

[0111] Therefore, for example, compared to an arrangement in which the blower fan F and the reverse conveying roller pair 42 are arranged side by side in the X-axis direction, the thickness of the opening and closing door 80 in the X-axis direction can be reduced, thereby reducing the size of the device.

[0112] External air outlet and upstream wall sheet edge receiving section like Figure 8 As shown, the upstream wall 61 includes a plurality of sheet edge receiving portions 62 that receive the trailing edge (upstream end in the discharge direction Ds) of the sheet S stacked on the sheet discharge tray 60. The plurality of sheet edge receiving portions 62 are arranged along the Y-axis direction. Each sheet edge receiving portion 62 protrudes in the sheet discharge direction Ds and extends in the Z-axis direction.

[0113] External air outlets 61s are disposed between adjacent sheet edge receiving portions 62 along the Y-axis direction. The portion of the upstream wall 61 in which the external air outlets 61s are formed is recessed upstream of the sheet edge receiving portion 62 in the sheet discharge direction Ds. In other words, the external air outlets 61s are formed in a recess in the upstream wall 61, which is recessed relative to the sheet edge receiving portion 62 at the trailing edge of the sheet S on the sheet discharge tray 60.

[0114] With this configuration, even when the trailing edge of the sheet stack on the sheet discharge tray 60 is in contact with the sheet edge receiving portion 62, the air discharged from the external air outlet 61s can flow upward through the recess and reach the upper surface of the sheet stack. That is, even when the amount of stacked sheets on the sheet discharge tray 60 increases, the cooling performance can be prevented from deteriorating due to obstruction of the airflow path from the external air outlet 61s.

[0115] Hereinafter, embodiments differing from the first embodiment will be described. In this hereinafter, unless otherwise stated, elements indicated by the same reference numerals as in the first embodiment will have substantially the same configuration and operation as those described in the first embodiment, and the differences from the first embodiment will be primarily described.

[0116] Example 2 As a second embodiment, the intermediate transport roller pair 21 can be omitted from the image forming apparatus 1 of the first embodiment. Additionally, the portion of the discharge guide 86 in the first embodiment that has the second vent 86s can be omitted. That is, air discharged from the first vents 65s and 66s (first openings) to the first transport path 101 can be discharged directly from the external air outlet 61s (second opening) without passing through the second vent 86s (fourth opening).

[0117] With the minimal impact on the conveying of sheet S due to the omission of a portion of the discharge guide 86, the configuration of this embodiment allows for a smoother airflow from the first conveying path 101 to the sheet discharge tray 60, thereby making it easier to cool the sheet S on the sheet discharge tray 60.

[0118] 3rd Embodiment As a third embodiment, such as Figure 9 As shown, the blower fan F can be located at a location other than the opening / closing door 80. In the example shown, the blower fan F is located at the end of the main frame 1A in the Y-axis direction.

[0119] An air inlet 80s' is formed on the end face of the main frame 1A in the Y-axis direction. The blower fan F is connected to the internal air outlet 82s via pipes (107 and 108) extending along the Y-axis direction. The first pipe 107 is disposed in the main frame 1A and connected to the exhaust side of the blower fan F. The second pipe 108 is disposed in the opening / closing door 80. One end of the second pipe 108 is connected to the first pipe 107, and the other end of the second pipe 108 forms the internal air outlet 82s. That is, in this embodiment, the first air path forming part 120 that guides airflow from the blower fan F to the first conveying path 101 includes a pipe (the second pipe 108) disposed in the opening / closing door 80. The flow path of the air discharged from the internal air outlet 82s is the same as the flow path in the first embodiment.

[0120] According to this embodiment, the blower fan F is located in a part other than the opening and closing door 80, thereby reducing the thickness of the opening and closing door 80 in the X-axis direction.

[0121] Example 4 As a fourth embodiment, such as Figure 10 As shown, air can be transported from one end of the sheet in the width direction (Y-axis direction) to the first transport path 101 and the second transport path 102.

[0122] like Figure 10As shown, an internal air outlet 84 is formed at each of the ends of the first conveying path 101 and the second conveying path 102 in the Y-axis direction. Air discharged from the blower fan F enters the first conveying path 101 and the second conveying path 102 through the internal air outlet 84, respectively, and cools the sheet S passing through the first conveying path 101 and the sheet S passing through the second conveying path 102.

[0123] In this embodiment, the blower fan F is disposed at the end of the first conveying path 101 and the second conveying path 102 in the Y-axis direction (second direction), the Y-axis direction being a horizontal direction orthogonal to the sheet discharge direction Ds (first direction). The first air path forming portion 120, which guides the airflow from the blower fan F to the first conveying path 101, includes an internal air outlet 84 as a first opening. The internal air outlet 84 opens at the end of the first conveying path 101 and the second conveying path 102 in the Y-axis direction.

[0124] Air entering the second conveying path 102 enters the first conveying path 101 through the first vent 65s and 66s described in the first embodiment. The flow path of the air after entering the first conveying path 101 is the same as in the first embodiment.

[0125] According to this embodiment, air can be conveyed to the first conveying path 101 without being blocked by the sheet S passing through the second conveying path 102. Therefore, for example, even when both sheets S pass through the first conveying path 101 and the second conveying path 102 at the same time, the sheet S in the first conveying path 101 can be effectively cooled.

[0126] According to this embodiment, by placing the blower fan F in a part other than the opening / closing door 80 as in the third embodiment, the thickness of the opening / closing door 80 in the X-axis direction can be reduced.

[0127] Example 5 As a fifth embodiment, such as Figure 11 As shown, the conveying path of the reverse conveying sheet S and the conveying path of the discharged sheet S do not need to be separated. In this embodiment, the first intermediate guide 65 and the second intermediate guide 66, which separated the first conveying path 101 and the second conveying path 102 in the first embodiment, are omitted. In this embodiment, the reverse conveying roller pair 42 and the switching guide 41 in the first embodiment are also omitted.

[0128] In this embodiment, the sheet discharge roller pair 22 functions as a reverse unit for reverse conveying of the sheet S. In the case of double-sided printing, the sheet discharge roller pair 22 conveys the sheet S having the first side with the image formed along the sheet discharge direction Ds, rotates in the reverse direction before the trailing edge of the sheet S along the sheet discharge direction Ds passes the roll gap of the sheet discharge roller pair 22, and conveys the sheet S in a direction opposite to the sheet discharge direction Ds.

[0129] The opening / closing door 80 is provided with a curved reverse guide 90. The leading edge of the sheet S, conveyed by the sheet discharge roller pair 22 in a direction opposite to the sheet discharge direction Ds, is guided along the curved portion of the reverse guide 90 toward the double-sided printing conveyor roller pair 51. An internal air outlet 90s is formed in the reverse guide 90.

[0130] Air from the blower fan F passes through the inner air outlet for 90 seconds, is discharged into the conveying space that also serves as the first conveying path 101 and the second conveying path 102, then passes through the second vent for 86 seconds and is discharged from the outer air outlet for 61 seconds to the sheet discharge tray 60.

[0131] According to this embodiment, while providing double-sided printing functionality, the number of parts can be reduced compared to the first embodiment, thereby reducing product costs.

[0132] Example 6 As a sixth embodiment, this technology can be applied to an image forming apparatus 1 specifically designed for single-sided printing, which does not have the following features: Figure 12 The double-sided printing function is shown. In this embodiment, air from the blower fan F is discharged from the inner air outlet 82s to the first conveying path 101, then passes through the second air outlet 86s and is discharged from the outer air outlet 61s to the sheet discharge tray 60.

[0133] According to this embodiment, compared with the fifth embodiment, the number of components can be further reduced, thereby reducing product costs.

[0134] Other variations In the above embodiments, the control unit of the image forming apparatus 1 can change the sheet interval, the air volume of the blower fan F, the sheet conveying speed, etc. during continuous printing based on the property information (sheet information) of the sheet S.

[0135] For example, the image forming apparatus 1 includes a sheet information acquisition unit that acquires sheet information such as the smoothness, gloss, and basis weight of the sheet S. The sheet information acquisition unit can be an operation panel that receives sheet information from a user, or a medium sensor disposed along the sheet transport path. When the sheet S has high smoothness or gloss, toner separation due to sliding friction with the transport guide tends to be significant, and when the sheets S are stacked on the sheet discharge tray 60, they tend to adhere tightly to each other, making adhesion between sheets S more likely. Therefore, compared to the case where the smoothness or gloss is below a predetermined value, when the smoothness or gloss of the sheet S is above a predetermined value, the sheet spacing widens, the airflow of the blower fan F increases, or the transport speed of the sheet S decreases. Thus, toner separation and adhesion between sheets can be suppressed.

[0136] In the above embodiments, the control unit of the image forming apparatus 1 can change the sheet interval, the air volume of the blower fan F, the sheet conveying speed, etc. during continuous printing based on the image information (print data) indicating the image to be formed on the sheet S.

[0137] For example, when a large amount of toner is transferred onto the sheet S during image formation, toner separation due to sliding friction with the transport guide tends to be significant. Furthermore, when the sheets S are stacked on the sheet discharge tray 60, the image surfaces tend to adhere tightly to each other, making adhesion between sheets S more likely. Therefore, compared to the case where the amount of toner determined to be less than a predetermined amount, when the amount of toner transferred to the sheet S is determined to be greater than a predetermined amount based on image information, the sheet spacing widens, the airflow of the blower fan F increases, or the transport speed of the sheet S decreases. Thus, toner separation and adhesion between sheets can be suppressed.

[0138] In the first to fifth embodiments described above, the control unit of the image forming apparatus 1 can change the sheet spacing, the air volume of the blower fan F, the sheet conveying speed, etc. during continuous printing, depending on whether the printing is single-sided or double-sided.

[0139] In double-sided printing, the toner image is transferred to both sides of the sheet S. Therefore, the image is formed on the surfaces of two overlapping sheets on the sheet discharge tray 60, with the sheet surfaces facing each other. This increases the likelihood of sheet adhesion. Consequently, in double-sided printing, compared to single-sided printing, the sheet spacing is wider, the airflow of the blower fan F is increased, or the conveying speed of the sheet S is reduced. This helps to suppress sheet adhesion.

[0140] To date, there have been instances where simply blowing air toward the outside of the image forming apparatus is insufficient to cool the sheet.

[0141] According to this disclosure, an image forming apparatus capable of adequately cooling a sheet can be provided.

[0142] Other embodiments While this disclosure has been described with reference to embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. The scope of the above claims should be given the broadest interpretation in order to cover all such modifications and equivalent structures and functions.

Claims

1. An image forming apparatus, comprising: A housing includes a stacking section and an upstream wall, on which sheets discharged along a sheet discharge direction intersecting a vertical direction are stacked. The upstream wall is disposed upstream of the stacking section in the sheet discharge direction and faces the end of the sheets stacked on the stacking section. A transfer section, at which a toner image is transferred onto the sheet; A fixing device, housed within the housing, and configured to heat the toner image on the sheet to fix the toner image onto the sheet; The discharge component is configured to discharge the sheet, on which the toner image has been fixed by the fixing device, from the inside to the outside of the housing along the sheet discharge direction; A reverse component configured to reverse the transport of the sheet that has already passed through the transfer section and the fixing device; A first transport guide is configured to separate a first transport path from a second transport path, the first transport path transporting the sheet from the fixing device toward the discharge member, and the second transport path transporting the sheet, which has been reverse-transported by the reversing member, toward the transfer unit. A fan, configured to generate airflow; A first air path forming part includes a first opening formed in the first conveying guide, the first air path forming part being configured to guide the airflow through the first opening to the first conveying path; as well as A second air path forming section includes a second opening formed in the upstream wall, the second air path forming section being configured to guide the airflow from the first delivery path through the second opening to the stacking section.

2. The image forming apparatus according to claim 1, wherein, The first conveying guide includes a first side portion forming the first conveying path and a second side portion forming the second conveying path, and, The first opening extends from the first side to the second side, allowing the airflow to be guided from the second conveying path to the first conveying path via the first opening.

3. The image forming apparatus according to claim 2, further comprising: The second conveying guide is disposed on the side opposite to the first conveying guide relative to the second conveying path. The first air path forming part includes a third opening formed in the second conveying guide, through which the airflow is guided from the fan to the second conveying path.

4. The image forming apparatus according to claim 3, further comprising: The third conveying guide is disposed on the side opposite to the first conveying guide relative to the first conveying path. The second air path forming part includes a fourth opening formed in the third conveying guide, such that the airflow is guided from the first conveying path to the second opening through the fourth opening.

5. The image forming apparatus according to claim 4, wherein, The third opening, the first opening, the fourth opening, and the second opening are arranged sequentially from upstream to downstream in the horizontal direction along the sheet discharge direction.

6. The image forming apparatus according to claim 5, wherein, The vertical opening range of the third opening overlaps with the vertical opening range of the first opening. The vertical opening range of the first opening overlaps with the vertical opening range of the fourth opening, and... The vertical opening range of the fourth opening overlaps with the vertical opening range of the second opening.

7. The image forming apparatus according to any one of claims 1 to 6, wherein, The housing includes: A main frame, including the stacked portion and the upstream wall, and the main frame having an opening formed at an end in a direction opposite to the sheet discharge direction; and An opening / closing unit is configured to move between an open position and a closed position, wherein in the open position, the opening / closing unit opens the opening to expose at least a portion of the second transport path to the outside of the image forming apparatus, and in the closed position, the opening / closing unit closes the opening, and... The fan is located in the opening and closing unit.

8. The image forming apparatus according to claim 7, wherein, The opening and closing unit includes a cover member forming the outer surface of the image forming apparatus and an air inlet formed in the cover member, through which air enters the image forming apparatus from the outside during fan rotation.

9. The image forming apparatus according to claim 8, wherein, The air inlet is formed on the end face of the opening and closing unit facing in a direction opposite to the sheet discharge direction; The fan is positioned between the air inlet and the second conveying path in the sheet discharge direction and above the reverse member, and is configured to overlap with the reverse member when viewed in the vertical direction.

10. The image forming apparatus according to any one of claims 1 to 6, wherein, The housing includes: The main frame includes the stacked portion and the upstream wall, and the main frame has an opening formed at an end on a side opposite to the sheet discharge direction. An opening / closing unit is configured to move between an open position and a closed position, wherein in the open position, the opening / closing unit opens the opening to expose at least a portion of the second transport path to the outside of the image forming apparatus, and in the closed position, the opening / closing unit closes the opening. The fan is housed within the main frame. The first air path forming unit includes a duct disposed in the opening and closing unit, the duct being configured to guide the airflow from the fan to the second delivery path.

11. The image forming apparatus according to claim 10, wherein, The fan is located at the end of the main frame in a horizontal direction orthogonal to the sheet discharge direction.

12. The image forming apparatus according to claim 1 or 2, wherein, The fan is located at the end of the first conveying path and the second conveying path in a horizontal direction orthogonal to the sheet discharge direction. The first opening is located at the end of the first conveying path and the second conveying path in the horizontal direction orthogonal to the sheet discharge direction in each of the first conveying path and the second conveying path.

13. The image forming apparatus according to any one of claims 1 to 6, further comprising: A roller pair is disposed between the fixing device and the discharge member, and is configured to convey the sheet that has passed through the fixing device to the discharge member; The direction of movement of the sheet at the roller pair is different from the direction of movement of the sheet at the discharge member. With the sheet bent between the roller pair and the discharge member, the first conveying guide is located outside the bent portion of the sheet; and At least a portion of the first opening is located upstream of the roller pair in the sheet conveying direction from the fixing device toward the discharge member.

14. The image forming apparatus according to any one of claims 1 to 6, wherein, The second opening is located at its lower end in the vertical direction at the same height as the upper surface of the stacked portion at its upstream end in the sheet discharge direction.

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