Image forming device

Abstract

To improve workability when opening a guide (sheet guide member) to remove a sheet left inside, for example.SOLUTION: A lock lever and an operating lever are provided on a sheet guide member such that a rotation axis direction of the lock lever for disengaging the sheet guide member from a housing crosses a rotation axis direction of the operating lever for adjusting pressing force of a pressure roller on a fixing roller.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus such as a copying machine or a printer that forms an image on a recording sheet using an electrophotographic method. [Background technology]

[0002] Conventionally, a known image forming device for forming an image on a sheet is configured to transfer an image formed on a photosensitive member to the sheet in a transfer section, fix the transferred image to the sheet in a fixing section, and discharge the sheet with the fixed image into a discharge tray at the top of the device.

[0003] In recent years, users have been demanding that the printer be able to handle various types of sheets, such as plain paper, envelopes, etc. To accommodate such various types of sheets, a known configuration is one in which an exterior cover on the side of the printer (or the rear of the printer) is opened and the sheet on which the image has been fixed in the fixing unit is ejected horizontally from the side of the printer.

[0004] Furthermore, in order to accommodate sheets such as envelopes, which have a narrower width in the direction perpendicular to the sheet conveyance direction than regular paper, a configuration is disclosed in which a pressure adjustment mechanism is provided in the fixing section to adjust the nip pressure on the sheet.

[0005] Patent Document 1 discloses a nip pressure adjustment mechanism that provides a pair of pressure adjustment levers on the left and right in the width direction of the sheet and operates the pressure adjustment levers to adjust the nip pressure between a heating roller in a fixing unit and a pressure roller pressed against the heating roller. The nip pressure between the heating roller and pressure roller in the fixing unit is adjusted by pressing down the pressure adjustment lever so that it is smaller after being pressed down than before being pressed down. When using envelopes, which are narrower than plain paper, the pressure adjustment lever is pressed down to reduce the nip pressure, and the lever is maintained in the position after being pressed down where the nip pressure is smaller than before being pressed down. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-106028 Summary of the Invention [Problem to be solved by the invention]

[0007] Furthermore, in conventional image forming apparatuses, sheets on which an image has been fixed in the fixing unit are fed from the horizontal direction toward the vertically upward direction along the side of the apparatus, and then toward the tray at the top of the apparatus. Therefore, in addition to the pressure adjustment mechanism described above, conventional image forming apparatuses are provided with guides (sheet guide members) and rollers in the section along the side of the apparatus between the fixing unit and the output tray at the top of the apparatus, which guide the sheet fed horizontally toward the vertically upward direction along the side of the apparatus.

[0008] The guide is provided so as to be openable and closable relative to the device body in order to remove sheets remaining in the fixing section or in the section along the side of the device. The guide is provided with a release lever that engages and disengages the guide from the device body. The guide is held in a position where it guides the sheet in the vertical direction by engaging the release lever with the device body, and can be retracted from the sheet guiding position by disengaging the release lever. The guide is also provided with the pressure adjustment lever described above. The pressure adjustment lever is provided in the guide engaged with the device body by the release lever, vertically lower than the release lever and closer to the rotation center of the guide than the release lever.

[0009] When removing the sheet remaining in the aforementioned section, if the remaining sheet is an envelope, the pressure adjustment lever is held in the depressed position when the guide is opened. In this case, the biasing force of the biasing member that presses the heat roller and pressure roller acts on the pressure adjustment lever, which is held in the depressed position. Therefore, if the pressure adjustment lever is held in the depressed position when the guide is opened, even if the engagement with the device body is released by the release lever, the force acting on the pressure adjustment lever acts as a load to maintain the guide's position, preventing the guide from being opened.

[0010] Therefore, when removing sheets remaining in the fixing section or in the section along the side of the device, it is preferable to release the pressure adjustment lever from its depressed position, then use the release lever to release the engagement with the device main body and open the guide.

[0011] That is, in the conventional image forming apparatus described above, there is a problem that the workability is reduced when removing the sheet remaining in the fixing section or in the section along the side of the apparatus.

[0012] SUMMARY OF THE INVENTION It is therefore an object of the present invention to improve the workability when opening a guide (sheet guide member), for example, when removing remaining sheets. [Means for solving the problem]

[0013] In order to achieve the above object, an image forming apparatus according to the present invention includes a fixing device having a heating roller that heats an unfixed image formed on a sheet and a pressure roller that pinches and presses the sheet against the heating roller, thereby fixing the unfixed image to the sheet; a housing that houses the fixing device and has a discharge section that discharges sheets that have passed through the fixing device to the outside of the image forming apparatus; an exterior cover that is provided inside the housing and can be opened and closed relative to the housing when the exterior cover is open; a sheet guide member that is provided inside the exterior cover and can be opened and closed relative to the housing when the exterior cover is open, the sheet guide member being movable between a closed position where it is closed to guide sheets discharged from the discharge section and an open position where it is open to allow an operator to access the fixing device; and an operating lever that is provided on the sheet guide member vertically below the lock lever and that moves the pressure roller, which is in a first pressing position where it presses the heating roller with a first pressing force, to a second pressing position where it presses the heating roller with a second pressing force that is smaller than the first pressing force, the operating lever rotating relative to the sheet guide member and taking a first position when the pressure roller is in the first pressing position and a second position when the pressure roller is in the second pressing position, wherein the lock lever and the operating lever are provided on the sheet guide member so that the direction of the rotation axis of the lock lever intersects with the direction of the rotation axis of the operating lever. [Effects of the Invention]

[0014] According to the present invention, it is possible to improve the workability when opening the sheet guide member, for example, when removing remaining sheets. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a perspective view showing the image forming apparatus when the joint cover is in the mounting position. [Figure 2]FIG. 2 is a perspective view showing the image forming apparatus when the joint cover is in the separated position. [Figure 3] FIG. 2 is a perspective view showing the image forming apparatus with the process cartridge removed. [Figure 4] FIG. 2 is a left side view showing the image forming apparatus when the joint cover is in the mounting position. [Figure 5] FIG. 2 is a left side view showing the image forming apparatus when the joint cover is in the separated position. [Figure 6] FIG. 10 is a perspective view of a conventional example in which the transport guide is closed. [Figure 7] FIG. 10 is a perspective view of a conventional example in which the transport guide is open. [Figure 8] FIG. 10 is a diagram illustrating a nip pressure adjusting mechanism in a conventional example. [Figure 9] FIG. 4 is a diagram for explaining a paper path in a normal mode in the present embodiment. [Figure 10] FIG. 4 is a diagram for explaining a paper path in an envelope mode in the present embodiment. [Figure 11] FIG. 4 is a perspective view of the conveying guide in the present embodiment in a closed state. [Figure 12] 4A and 4B are diagrams for explaining a transport guide opening / closing mechanism in the present embodiment. [Figure 13] FIG. 10 is a perspective view of a transport guide in a closed state in a second embodiment. [Figure 14] 10A and 10B are diagrams illustrating a transport guide opening and closing mechanism in a second embodiment. [Figure 15] FIG. 10 is a perspective view of a transport guide in a closed state in the second embodiment. [Figure 16] 10A and 10B are diagrams illustrating a transport guide opening and closing mechanism in a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] The following describes embodiments of the present invention with reference to the drawings. Note that the dimensions, materials, shapes, relative positions, etc. of the components described below are not intended to limit the scope of the present invention unless otherwise specified.

[0017] <Overall configuration of image forming apparatus> The overall configuration of the image forming apparatus will be described with reference to Figures 1 to 5. Figure 1 is a perspective view showing the image forming apparatus when the joint cover is in the mounted position. Figure 2 is a perspective view showing the image forming apparatus when the joint cover is in the separated position. Figure 3 is a perspective view showing the image forming apparatus with the process cartridge removed. Figure 4 is a left side view showing the image forming apparatus when the joint cover is in the mounted position. Figure 5 is a left side view showing the image forming apparatus when the joint cover is in the separated position.

[0018] In FIG. 1, the downstream side of the image forming apparatus in the direction in which the feed tray 31 is pulled out and the opening side of the discharge tray 32 are defined as the front side of the image forming apparatus, and the upstream side of the image forming apparatus in the direction in which the feed tray 31 is pulled out are defined as the rear side of the image forming apparatus. Furthermore, when viewed from the front side of the image forming apparatus, the side closest to the left is defined as the left side of the image forming apparatus, and the side closest to the right is defined as the right side of the image forming apparatus. Furthermore, the vertically upper side of the image forming apparatus is defined as the upper side of the image forming apparatus, and the vertically lower side is defined as the lower side of the image forming apparatus. Based on these definitions, the front-rear, left-right, and up-down directions are shown in FIG. 1. The directions shown in FIG. 2 and subsequent figures correspond to the directions shown in FIG. 1. The horizontal direction, which is the direction of the axis that serves as the center of oscillation (described later), is defined as the left-right direction perpendicular to the up-down direction, which is the vertical direction of the image forming apparatus.

[0019] 1, this image forming apparatus includes a printer unit 1 as an example of a housing, a joint cover 2 provided on the printer unit 1, a reading device 3 provided on the joint cover 2, and an automatic feeder 4 provided on the reading device 3. The joint cover 2, the reading device 3, and the automatic feeder 4 are examples of a first movable part.

[0020] The configuration of the printer unit 1 and the joint cover 2 will now be described. As shown in Fig. 2, a pair of first hinge units 11a, 11b that allow the printer unit 1 and the joint cover 2 to swing about a first axis O1 are provided on the rear side of each unit. This allows the joint cover 2 to be swingable on the printer unit 1 around the first axis O1 in the horizontal direction, which is perpendicular to the vertical direction, on the rear side of the printer unit 1.

[0021] As shown in FIG. 2, the printer unit 1 is covered from the outside by a resin body cover 20. The body cover 20 has a left side cover 23, a right side cover 24, a front cover 22, and a rear cover (exterior cover) 21. The left side of the printer unit 1 is covered by the side cover 23, and the right side of the printer unit 1 is covered by the side cover 24. As shown in FIG. 1, a feed tray 31 is provided between the side covers 23 and 24 on the front side of the printer unit 1 so as to be able to be pulled out toward the front, and the front side of the printer unit 1 above the feed tray 31 is covered by the front cover 22. As shown in FIG. 2, a rear cover 21, which serves as an example of a second movable unit (described later), is provided between the side covers 23 and 24 on the rear side of the printer unit 1 so as to be able to swing. The rear cover 21 is provided in a position facing a sheet transport path 30, which serves as a second sheet transport unit (described later).

[0022] The joint cover 2 is configured to be movable between a first mounting position, shown in Fig. 1, where it is mounted on top of the printer unit 1, and a first separated position, shown in Fig. 2, where it is separated upward from the printer unit 1 around a first axis O1. An upper opening 27, which is a first opening that exposes the image forming unit 15 upward when the joint cover 2 is in the first separated position, is formed on the top of the printer unit 1. In other words, the upper opening 27 is a space surrounded by the upper edges of the front cover 22, side covers 23 and 24, and rear cover 21.

[0023] As described above, the first movable unit, including the joint cover 2, the reader 3, and the automatic feeder 4, is supported relative to the printer unit 1 so as to be swingable about the first hinges 11a and 11b. Furthermore, the first movable unit is supported relative to the printer unit 1 so as to be movable about the first center 01 by a movement mechanism configured as follows. The movement mechanism includes an arm 33 and a spring 39. The arm 33 has a boss 34 at one end rotatably supported in a hole 35 in the printer unit 1, and a boss 36 at the other end movably supported along a rail 37 of the joint cover 2. One end of the spring 39 is fixed to the joint cover 2, and the other end is fixed to the boss 36 side of the arm 33. When the joint cover 2 is rotated relative to the printer unit 1 toward the first separated position, the arm 33 rotates about the boss 34, while the boss 34 slides in one direction along the rail 37. At that time, the spring 39 contracts, applying an opening force to the joint cover 2. Meanwhile, when the joint cover 2 is rotated toward the first placement position relative to the printer unit 1, the arm 33 rotates about the boss 34, and the boss 34 slides along the rail 37 in the opposite direction to the one direction. At that time, the spring 39 expands (a restoring force), applying a force to the joint cover 2 that resists the closing force due to its own weight. In this way, the opening and closing operation of the joint cover 2 is assisted by the force of the spring, improving operability.

[0024] The printer unit 1 has an image forming unit 15 that forms an image on a sheet. As shown in FIG. 2, the image forming unit 15 has four cartridges 25K, 25Y, 25M, and 25C. These cartridges 25K, 25Y, 25M, and 25C are located in a front portion of the printer unit 1 away from the first axis O1 and are removably attached to the printer unit 1. Cartridge 25K corresponds to black, cartridge 25Y corresponds to yellow, cartridge 25M corresponds to magenta, and cartridge 25C corresponds to cyan. These cartridges are arranged in this order along the sheet transport direction of a transport belt 29 (an example of a first sheet transport unit) shown in FIG. 4. Each of the cartridges 25K, 25Y, 25M, and 25C includes a toner container, a photosensitive drum serving as an image carrier, and a developing device, a charger, and other process means acting on the photosensitive drum. The charger is a charging device that uniformly charges the surface of the photosensitive drum. The developer is a developing device that develops the latent image formed on the surface of the photosensitive drum with toner. Note that the process devices that act on the photosensitive drum are not limited to the developer and charger. Each of the cartridges 25K, 25Y, 25M, and 25C is an example of a replaceable part that requires replacement.

[0025] 3, the image forming apparatus has four LED heads 26K, 26Y, 26M, and 26C. These LED heads 26K, 26Y, 26M, and 26C are suspended from the lower surface side of the joint cover 2. The LED heads 26K, 26Y, 26M, and 26C are exposure means that irradiate and expose the photosensitive drums of the respective cartridges 25K, 25Y, 25M, and 25C with light according to image information.

[0026] 4, a conveyor belt 29 is provided within the printer unit 1 as an example of a first sheet conveying unit that conveys sheets. The conveyor belt 29 is provided below the image forming unit 15 in the vertical direction and conveys sheets fed from a feed tray 31. Here, the conveyor belt 29 as the first sheet conveying unit is a conveying body (sheet carrier) that carries and conveys sheets. Therefore, this image forming apparatus is an image forming apparatus in which toner images of each color are transferred in succession, superimposed on one another, onto a sheet carried on the conveyor belt 29 by the image forming unit 15.

[0027] Furthermore, a sheet transport path 30 serving as an example of a second sheet transport section is provided within the printer section 1 at the rear side of the printer section 1, which transports sheets along a vertical side surface of the printer section 1. The sheet transport path 30 is composed of rollers for transporting the sheets, a guide section for guiding the sheets, and the like (not shown). An operating section (not shown) drives the image forming section 15 and the sheet transport section, so that the sheets stored in the feed tray 31 are transported by the transport belt 29, an image is formed in the image forming section 15, and the sheets are discharged onto the discharge tray 32 via the sheet transport path 30.

[0028] As described above, the rear cover 21, which is an example of the second movable part, is located between the side covers 23 and 24 that constitute the main body cover 20 on the rear side of the printer unit 1, and is located in a position opposite the sheet transport path 30.

[0029] The configurations of the printer unit 1 and rear cover 21 will now be described. As shown in Figure 2, a pair of second hinges 12a, 12b are provided between the printer unit 1 and the rear cover 21 on the rear side of the printer unit 1 and the lower side of the rear cover 21, allowing the printer unit 1 and the rear cover 21 to pivot about the second axis O2. This allows the rear cover 21 to pivot on the printer unit 1 around the second axis O2, which is in the horizontal direction and perpendicular to the vertical direction, on the rear side of the printer unit 1. The second axis O2 of the rear cover 21 is located vertically below the first axis O1 of the joint cover 2 on the rear side of the printer unit 1.

[0030] The rear cover 21 is configured to be movable between a second placement position placed on the rear surface of the printer unit 1 shown in Fig. 4 and a second separated position rotated rearward from the printer unit 1 about a second axis O2 shown in Fig. 5. A rear opening 28, which is a second opening that exposes the sheet transport path 30 to the rear side when the rear cover 21 is in the second separated position, is formed on the rear side of the printer unit 1. In this way, the rear cover 21 is a second movable part that is movable between the second placement position placed on the printer unit 1 so as to cover the rear opening 28, which is the second opening formed on the rear side of the printer unit 1, and the second separated position separated from the printer unit 1 so as to open the rear opening 28 of the printer unit 1.

[0031] The reading device 3 is placed on the joint cover 2 as shown in Fig. 4. The reading device 3 has a placement surface 3a on which a document to be read is placed, and a reading unit 3b that moves and reads the image of the document on the placement surface 3a. Here, the reading device 3, together with the joint cover 2, constitutes a first movable unit that can swing relative to the printer unit 1. The configuration of the reading unit 3b is well known, so a detailed description will be omitted.

[0032] The automatic feeder 4 is placed on the reading device 3 as shown in Fig. 4. The automatic feeder 4 also includes a document feeder (not shown) and a document transport unit 4a that separates the documents set in the document feeder one by one and transports them toward the reading unit 3b, which is in a stopped position. The images of the documents transported by the document transport unit 4a are read by the reading unit 3b during transport, and the documents are discharged to a document discharge unit (not shown). Here, the automatic feeder 4, together with the joint cover 2 and the reading device 3, constitute a first movable unit that can swing relative to the printer unit 1.

[0033] <Composition of joint cover and rear cover> Next, the configurations of the printer unit 1, joint cover 2, and rear cover 21 in this embodiment will be described with reference to FIGS.

[0034] As described above, the joint cover 2, reading device 3, and automatic feeder 4 as the first movable part are configured to be displaceable between the first placement position shown in FIG. 4, where they are placed on the printer unit 1 as the main body part, and the first separated position shown in FIG. 5, where they rotate upward around the first axis O1.

[0035] The main body cover 20 is formed with an upper opening 27 that exposes the image forming unit 15 upward when the joint cover 2 is in the first separated position.

[0036] As a result, the cartridges 25K, 25Y, 25M, and 25C of the image forming unit 15 can be replaced through the upper opening 27, and jammed sheets on the conveyor belt 29 can be removed.

[0037] On the other hand, as described above, the rear cover 21 as the second movable part is configured to be displaceable between the second placement position shown in FIG. 4, in which it is placed on the rear of the printer unit 1, and the second separated position shown in FIG. 5, in which it rotates toward the rear side around the second axis O2.

[0038] A rear opening 28 is formed so that the sheet transport path 30 is exposed to the rear side when the rear cover 21 is in the second separated position.

[0039] As a result, jammed sheets in the sheet transport path 30 can be cleared through the rear opening 28.

[0040] <Conventional nip pressure adjustment mechanism> A conventional nip pressure adjustment mechanism will be described with reference to Figures 6 to 8. Figures 6 and 7 are perspective views of a conventional image forming apparatus in which a conveyance guide is in a closed state and an open state. Figure 8 is a diagram of an image forming apparatus showing the conventional nip pressure adjustment mechanism.

[0041] First, a state in which the transport guide of a conventional image forming apparatus is closed will be described with reference to FIG.

[0042] As shown in Fig. 6, when rear cover 21 is rotated from a closed state (closed position) relative to the image forming apparatus to an open state (open position), a conveying guide (sheet guide member) 131 is provided integrally with the image forming apparatus on the rear side of the image forming apparatus. In other words, conveying guide 131 is a member provided inside rear cover 21. By opening conveying guide 131, a user is permitted to access fixing device 40. For example, when a paper jam occurs inside image forming apparatus 1, conveying guide 131 can be opened to access the inside of image forming apparatus 1.

[0043] The conveyance guide 131 is provided with a pair of left and right lock release levers (lock levers) 132a, 132b, first conveyance guide ribs 133a, 133b, and pressure adjustment levers (operation levers) 134a, 134b in the width direction of the paper conveyance direction. The pressure adjustment levers 134a, 134b are disposed vertically below the release levers 132a, 132b. The first conveyance guide rib 133a is located between the lock release lever 132a and the pressure adjustment lever 134a in the vertical direction of the image forming apparatus.

[0044] The image forming apparatus is also provided with a pair of swing levers (support members) 135a and 135b that are pivotally supported on the left and right sides of the image forming apparatus in the width direction of the paper conveyance direction and are configured to be rotatable.

[0045] The lock release lever 132a is pivotally supported by the conveyance guide 131 and can be operated in the direction to release the lock. By releasing the lock release lever 132a, the conveyance guide 131 becomes rotatable relative to the image forming apparatus. Both of the lock release levers (lock levers) 132a and 132b rotate around a rotation axis in the vertical direction. On the other hand, both of the pressure adjustment levers (operation levers) 134a and 134b rotate around a rotation axis in a direction perpendicular to the vertical direction. In other words, the direction of the rotation axis of the lock lever and the direction of the rotation axis of the operation lever intersect.

[0046] Next, a state in which the transport guide of the conventional image forming apparatus is closed will be described with reference to FIG.

[0047] As shown in FIG. 7 , when the conveying guide 131 rotates from a closed state to an open state relative to the image forming apparatus, the conveying guide 131 is provided with a first conveying roller 136. The image forming apparatus also has a second conveying roller 137, a fixing pressure roller 138, and a fixing heat roller 139. A sheet of paper with an unfixed image formed thereon and conveyed to the fixing device passes between the fixing pressure roller 138 and the fixing heat roller 139. In this way, the image is fixed to the sheet of paper. When the conveying guide 131 is in an open state, the sheet of paper that has passed through the fixing device is discharged from the discharge section of the fixing device to the outside of the image forming apparatus 1. The discharge section may be formed by a frame of the image forming apparatus 1 that supports the fixing device. Here, the discharge port through which the sheet of paper is discharged to the outside of the image forming apparatus 1 is referred to as the discharge section.

[0048] Furthermore, a nip pressure adjustment mechanism in a conventional example will be described with reference to Fig. 8. As shown in Fig. 8, a conveying guide 131 is provided with a lock release lever 132a, a first conveying guide rib 133a, a pressure adjustment lever 134a, and a first conveying roller 136, and is pivotally supported by the image forming apparatus so as to be rotatable relative to the image forming apparatus.

[0049] The lock release lever 132a is pivotally supported on the conveying guide 131 and is configured to be rotatable relative to the conveying guide 131. By gripping the lock release lever 132a and the first conveying guide rib 133a with fingers and operating the lock release lever 132a in the direction of releasing it, the conveying guide 131 can be opened and closed relative to the image forming apparatus.

[0050] The image forming apparatus also includes a swing lever (support member) 135a, a second conveying roller 137, a fixing pressure roller 138, a fixing heat roller 139, and a fixing biasing member 140a. The fixing biasing members 140a and 140b are configured as a pair on the left and right in the width direction of the paper conveyance direction.

[0051] The swing lever 135a is pivotally supported by the image forming apparatus and is configured to be rotatable relative to the image forming apparatus.

[0052] The pressure roller 138 is pivotally supported by the swing lever 135a and is configured to be rotatable relative to the swing lever 135a.

[0053] The second conveying roller 137 and the fixing heating roller 139 are supported by a shaft of the image forming apparatus and are configured to be rotatable relative to the image forming apparatus.

[0054] The fixing biasing member 140a has one end attached to the image forming apparatus and the other end attached to the swing lever 135a, and is capable of biasing the swing lever 135a toward the image forming apparatus.

[0055] As described above, the nip pressure between the fixing pressure roller 138 and the fixing heat roller 139 is applied via the fixing biasing member 140a and the swing lever 135a.

[0056] On the other hand, in recent years, from the viewpoint of improving media compatibility, users have been demanding compatibility with various types of sheets. Therefore, for example, when dealing with envelopes, which are narrower than normal sheets, it is necessary to vary the nip pressure between the fixing pressure roller 138 and the fixing heat roller 139 in the envelope mode in order to maintain image quality. The need for varying the nip pressure in the envelope mode will be explained below.

[0057] The fixing pressure roller 138 is biased by a pair of fixing biasing members 140a and 140b arranged left and right in the width direction of the paper transport direction, so the fixing pressure roller 138 bends in the center of the width direction of the paper transport direction, and the nip pressure becomes lower than at both ends.

[0058] Therefore, in the envelope mode, it is necessary to reduce the nip pressure at the center in the width direction of the paper transport direction.

[0059] As shown in FIG. 8, the pressure adjusting lever 134 a in the conventional example is pivotally supported by the conveying guide 131 and is configured to be rotatable relative to the conveying guide 131 .

[0060] When the pressure adjusting lever 134a is rotated and the contact of the holding plane with the swing lever 135a increases, the swing lever 135a is rotated, so that the nip pressure between the fixing pressure roller 138 and the fixing heat roller 139 can be reduced against the biasing force of the fixing biasing member 140a.

[0061] In the above-mentioned conventional example, if paper remains near the conveying roller of the fixing device, the remaining paper can be removed by operating the lock release lever 132a, which is supported on the conveying guide 131, in the direction of release and then opening the conveying guide 131.

[0062] On the other hand, if the pressure adjustment lever 134a pivotally supported by the conveying guide 131 is in the pressed-down position, opening the conveying guide 131 separates the holding planes of the swing lever 135a and the pressure adjustment lever 134a, and the pressure adjustment lever 134a is pushed up by the swing lever 135a. If the conveying guide 131 were opened with the pressure adjustment lever 134a pressed down, the pushed-up pressure adjustment lever 134a would come into contact with the operator's fingers, so the operator had to first push up the pressure adjustment levers 134a and 134b and then open the conveying guide 131.

[0063] The above-described conventional example has a problem in that when removing paper remaining near the conveying roller of the fixing device, maintenance becomes difficult.

[0064] <Paper paths in normal mode and envelope mode in this embodiment> The paper paths in the normal mode and the envelope mode in this embodiment will be described with reference to Figures 9 and 10. Figures 9 and 10 are diagrams for explaining the paper paths in the normal mode and the envelope mode in this embodiment.

[0065] First, the paper path in the normal mode in this embodiment will be described with reference to Fig. 9. As shown in the paper position (a) in Fig. 9, in the normal mode, paper is fed from the paper feed tray 51, passes through a curved sheet transport path in the vertical direction, and then enters the image forming unit 15.

[0066] As shown in the paper position (b) of Figure 9, in the normal mode, the paper passes horizontally through the image forming unit 15, passes through the sheet transport path formed by the nip portion between the fixing pressure roller 138 and the fixing heat roller 139, and the nip portion between the second transport roller 136 and the second transport roller 137, and then enters the curved sheet transport path.

[0067] As shown in the paper position (c) in FIG. 9, in the normal mode, the paper passes through the sheet transport path in the vertical direction and is then discharged onto the paper discharge tray 52.

[0068] Next, a case where paper remains near the conveying roller of the fixing device in the paper path in the normal mode will be described.

[0069] One example of a condition that can cause a jam is when paper is left in paper feed tray 32 for two to three days in a highly humid environment, absorbing moisture and stretching the entire paper. Furthermore, after the paper passes through the nip of the fixing device, the moisture in the paper decreases only on the side of fixing heating roller 139, leaving only one side of the paper shorter. As a result, the paper curls due to the difference in length between the front and back sides of the paper, and the paper may get caught in the nip between first conveyor roller 136 and second conveyor roller 137, causing a jam.

[0070] Next, the paper path in the envelope mode in this embodiment will be described with reference to FIG.

[0071] Because envelopes are thicker than normal sheets, there is a possibility that they may be damaged if they pass through a sheet transport path that is curved vertically. Therefore, it is desirable to form a horizontal sheet transport path and discharge the envelopes to the paper output tray of rear cover 21 while rear cover 21 is open from the image forming apparatus.

[0072] As shown in the paper position (a) of FIG. 10, in the envelope mode, paper is fed from a multi-tray (not shown) and enters the image forming unit 15 in the horizontal direction.

[0073] As shown in the paper position (b) of Figure 9, in the envelope mode, the sheet passes horizontally through the image forming unit 15 and passes through the sheet transport path formed by the nip between the fixing pressure roller 138 and the fixing heat roller 139, and the nip between the second transport roller 136 and the second transport roller 137.

[0074] As shown in the paper position (c) of FIG. 9, in the envelope mode, the paper passes through the paper discharge port on the rear cover 21 side and is then discharged onto the paper discharge tray on the rear cover 21.

[0075] In the paper path in envelope mode, if paper remains near the conveying roller of the fixing device, the paper may get caught in the nip between second conveying roller 136 and second conveying roller 137 under the same conditions as in normal mode, causing a jam.

[0076] <Conveyor guide opening / closing mechanism in this embodiment> The transport guide opening / closing mechanism of this embodiment will be described with reference to Figures 11, 7, and 12. Figures 11 and 7 are perspective views of the transport guide of the image forming apparatus according to this embodiment in a closed state and an open state. Figure 12 is a diagram of the image forming apparatus showing the transport guide opening / closing mechanism of this embodiment.

[0077] This embodiment is configured to solve the problem of the conventional example in that if the conveying guide 131 is opened while the pressure adjustment lever 134a is pressed down, the pressed-up pressure adjustment lever 134a may come into contact with the operator's fingers.

[0078] First, the state in which the transport guide of the image forming apparatus in this embodiment is closed will be described with reference to Fig. 11. As shown in Fig. 11, when the rear cover 21 rotates from a closed state to an open state relative to the image forming apparatus, a transport guide 131 is provided integrally with the image forming apparatus on the rear side of the image forming apparatus.

[0079] The conveying guide 131 is provided with a pair of conveying guide lock release levers 232a and 232b, first conveying guide ribs 233a and 233b, and pressure adjustment levers 134a and 134b, which are arranged widthwise in the paper conveying direction. In the vertical direction of the conveying guide 131, the conveying guide lock release lever 232a, the first conveying guide rib 233a, and the pressure adjustment lever 134a are positioned in this order from the top.

[0080] The image forming apparatus is also provided with a pair of swing levers 135a and 135b that are pivotally supported on the left and right sides of the image forming apparatus in the width direction of the paper conveyance direction and are configured to be rotatable.

[0081] The conveying guide lock release lever 232a is pivotally supported on the conveying guide 131 and can be operated in the direction to release the lock. By releasing the conveying guide lock release lever 232a, the conveying guide 131 becomes rotatable relative to the image forming apparatus.

[0082] Next, a state in which the conveying guide 131 of the image forming apparatus according to this embodiment is open will be described with reference to FIG.

[0083] 7, when the conveying guide 131 rotates from a closed state to an open state relative to the image forming apparatus, the conveying guide 131 is provided with a first conveying roller 136. The image forming apparatus is also provided with a second conveying roller 137, a fixing pressure roller 138, and a fixing heat roller 139.

[0084] Furthermore, the transport guide opening / closing mechanism in this embodiment will be described with reference to Fig. 12. As shown in Fig. 12, the transport guide 131 is provided with a transport guide lock release lever 232a, a first transport guide rib 233a, a pressure adjustment lever 134a, and a first transport roller 136, and is pivotally supported by the image forming apparatus so as to be rotatable.

[0085] The transport guide lock release lever 232a is pivotally supported by the transport guide 131 and is configured to be rotatable in the left-right direction of the device around a rotation shaft 232P provided on the transport guide 131. By gripping the transport guide lock release lever 232a and the first transport guide rib 233a with fingers and operating the lock release lever 232a in a direction to release it, the engagement between the protrusion 241a provided on the transport guide lock release lever 232a and the engagement portion 243a provided on the image forming device is released, and the transport guide 131 becomes openable and closable.

[0086] On the other hand, the pressure adjustment lever 134a is pivotally supported by the conveying guide 131 and is configured to be rotatable in the up-down direction of the device relative to the conveying guide 131. The conveying guide 131 can be opened and closed by gripping the pressure adjustment lever 134a with the fingers and pushing it upward in the direction to release the pressure adjustment lever 134a.

[0087] In this embodiment, the operating direction for releasing the transport guide lock release lever 232a and the operating direction for releasing the pressure adjustment lever 134a are configured to be approximately perpendicular. This makes it possible to prevent the pressure adjustment lever 134a from coming into contact with a finger while operating the transport guide lock release lever 232a. To operate the transport guide lock release lever 232a, the first transport guide rib 233a and the transport guide lock release lever 232a are held with the fingers in the left-right direction of the device, and this operation area is the area indicated by G in the figure. On the other hand, the operating area of the pressure adjustment lever 134a is the area indicated by F in the figure. By arranging the holding direction of the transport guide lock release lever 232a to be approximately perpendicular to the operating direction of the adjustment lever 134a, fingers will not enter the operating area of the pressure adjustment lever 134a and will not come into contact with it.

[0088] <Jam Clearance Procedure in This Embodiment> The jam handling procedure of this embodiment will be described in detail with reference to Figures 11 and 12. In the normal mode, paper may get caught in the nip between the first conveyor roller 136 and the second conveyor roller 137, causing a jam.

[0089] First, as shown in FIG. 11, the rear cover 21 is rotated to an open position from the image forming apparatus, making the conveying guide lock release lever 232a operable.

[0090] Next, as shown in Figure 12, by grasping the transport guide lock release lever 232a and the first transport guide rib 233a with your fingers and operating the transport guide lock release lever 232a in the direction of releasing it, the transport guide 131 can be opened and closed, making it possible to clear jams.

[0091] In the normal mode, the pressure adjusting lever 134a is pushed up to the released position, so there is no need to operate the pressure adjusting lever 134a.

[0092] On the other hand, in the envelope mode, the paper may get caught in the nip between the first conveying roller 136 and the second conveying roller 137, causing a jam.

[0093] In the envelope mode, the paper is discharged to the paper discharge tray of the rear cover 21 with the rear cover 21 open from the image forming apparatus, so there is no need to open the rear cover 21 from the image forming apparatus.

[0094] 12, in the envelope mode, the pressure adjustment lever 134a is in the pressed-down position (second pressing position), so the pressure adjustment lever 134a is pushed up with a finger and moved in the direction of the pressed-up position (first pressing position) where the pressure adjustment lever 134a is released. At the second pressing position, the pressure with which the fixing pressure roller presses the fixing heat roller is smaller than at the first pressing position.

[0095] Next, as shown in Figure 12, as in the normal mode, by grasping the transport guide lock release lever 232a and the first transport guide rib 233a with your fingers and operating the transport guide lock release lever 232a in the direction of releasing it, the transport guide 131 can be opened and closed, making it possible to clear jams.

[0096] As a second jam removal procedure, as shown in Figure 12, in envelope mode, while the pressure adjustment lever 134a is in the depressed position, it is also possible to grasp the conveyance guide lock release lever 232a and the first conveyance guide rib 233a with your fingers and operate them in the direction to release the conveyance guide lock release lever 232a. In this procedure, while holding the conveyance guide lock release lever 232a and the first conveyance guide rib 233a, your fingers operate to open the conveyance guide 131, which causes the pressure adjustment lever 134a to return from the envelope mode position to the normal mode position. Because your fingers are in a position holding the conveyance guide lock release lever 232a and the first conveyance guide rib 233a and are not within the operating range of the pressure adjustment lever 134a, you can open the conveyance guide 131 without your fingers coming into contact with the pressure adjustment lever 134a.

[0097] <Conveyor guide opening / closing mechanism in the second embodiment> The transport guide opening / closing mechanism of the second embodiment will be described with reference to Figures 13 and 14. Figure 13 is a perspective view showing the transport guide of the image forming apparatus according to the second embodiment in a closed state and an open state. Figure 14 is a diagram of the image forming apparatus showing the transport guide opening / closing mechanism of the second embodiment.

[0098] The second embodiment is configured to solve the problem of the conventional example in that if the conveying guide 131 is opened while the pressure adjustment lever 134a is pressed down, the pressed-up pressure adjustment lever 134a may come into contact with the operator's fingers.

[0099] First, the state in which the transport guide of the image forming apparatus in the second embodiment is closed will be described with reference to FIG.

[0100] As shown in FIG. 13, when the rear cover 21 rotates from a closed state to an open state relative to the image forming apparatus, a conveyance guide 131 is provided integrally with the image forming apparatus on the rear side of the image forming apparatus.

[0101] A pair of conveyance guide lock release buttons 332a, 332b and pressure adjustment levers 134a, 134b are provided on the left and right sides of the conveyance guide 131 in the width direction of the paper conveyance direction. In the vertical direction of the image forming apparatus, the conveyance guide lock release button 332a and pressure adjustment lever 142a are located in this order from the top.

[0102] Next, the transport guide opening / closing mechanism in the second embodiment will be described with reference to Fig. 14. As shown in Fig. 14, the transport guide 131 is provided with a transport guide lock release button 332a, a pressure adjustment lever 134a, and a first transport roller 136, and the transport guide 131 is pivotally supported by the image forming apparatus and is configured to be rotatable relative to the image forming apparatus.

[0103] The transport guide lock release button 332a is held by the transport guide 131 so as to be able to translate in the front-to-rear direction of the device. A transport guide lock 341a is supported on a rotation shaft 341P in the transport guide 131 so as to be able to rotate in the left-to-right direction of the device. By pressing the transport guide lock release button 332a towards the front of the device, the transport guide lock 341a is pressed and rotated towards the left of the device, thereby releasing the engagement with the lock engagement part 343a of the device, and the transport guide 131 becomes openable and closable.

[0104] On the other hand, the pressure adjustment lever 134a is pivotally supported by the conveying guide 131 and is configured to be rotatable relative to the conveying guide 131. By pushing the pressure adjustment lever 134a upward with a finger, the conveying guide 131 can be opened and closed by operating the pressure adjustment lever 134a in the release direction.

[0105] In the second embodiment, the transport guide 131 is unlocked by pressing the transport guide lock release button 332a toward the front of the device, allowing the transport guide 131 to be opened and closed. This prevents the pressure adjustment lever 134a from coming into contact with a finger while the transport guide lock release button 332a is being released. To operate the transport guide lock release button 332a, the button 332a is pressed with a finger, and the working area is the area indicated by G in the figure. Meanwhile, the operating area of the pressure adjustment lever 134a is the area indicated by F in the figure. By setting the pressing direction of the transport guide lock release button 332a to be approximately perpendicular to the operating direction of the adjustment lever 134a, fingers will not enter the operating area of the pressure adjustment lever 134a and will not come into contact with it.

[0106] As in the first embodiment, in the second embodiment, two jam clearance procedures are possible in the envelope mode. In the first jam clearance procedure, as shown in Figure 14, since the pressure adjustment lever 134a is in the depressed position in the envelope mode, the pressure adjustment lever 134a is pushed up with a finger and operated in the direction of the pushed-up position to release the pressure adjustment lever 134a.

[0107] Next, as shown in FIG. 14, by pressing the transport guide lock release button 332a, the transport guide lock 341a is released from the lock engagement portion 343a of the device, allowing the transport guide 31 to be opened and closed, enabling jam clearance.

[0108] As a second jam removal procedure, as shown in Figure 14, in envelope mode, it is also possible to open and close the conveyance guide 131 by pressing the conveyance guide lock release button 332a while the pressure adjustment lever 134a is in the depressed position. In this procedure, the conveyance guide 131 opens while the finger remains in the depressed position of the conveyance guide lock release button 332a, and at that time the pressure adjustment lever 134a returns from the envelope mode position to the normal mode position. Because the finger is in the position where the conveyance guide lock release button 332a is pressed and is not within the operating range of the pressure adjustment lever 134a, the conveyance guide 131 can be opened without the finger coming into contact with the pressure adjustment lever 134a.

[0109] <Transport guide opening / closing mechanism in the third embodiment> A transport guide opening / closing mechanism of the third embodiment will be described with reference to Figures 15 and 16. Figure 15 is a perspective view showing the transport guide of the image forming apparatus according to the third embodiment in a closed state and an open state. Figure 16 is a diagram of the image forming apparatus showing the transport guide opening / closing mechanism of the third embodiment.

[0110] The third embodiment is configured to solve the problem of the conventional example in that if the conveying guide 131 is opened while the pressure adjustment lever 134a is pressed down, the pressed-up pressure adjustment lever 134a may come into contact with the operator's fingers.

[0111] First, the state in which the transport guide of the image forming apparatus in the third embodiment is closed will be described with reference to Fig. 15. As shown in Fig. 15, when the rear cover 21 rotates from a closed state to an open state relative to the image forming apparatus, a transport guide 131 is provided integrally with the image forming apparatus on the rear side of the image forming apparatus.

[0112] The conveying guide 131 is provided with a pair of conveying guide lock release levers 132a and 132b, first conveying guide ribs 133a and 133b, and pressure adjustment levers 434a and 434b, arranged widthwise in the paper conveying direction. In the vertical direction of the conveying guide 131, the conveying guide lock release lever 132a, the first conveying guide rib 133a, and the pressure adjustment lever 434a are positioned in this order from the top.

[0113] Next, the transport guide opening / closing mechanism in the third embodiment will be described with reference to Fig. 16. As shown in Fig. 16, the transport guide 131 is provided with a transport guide lock release lever 132a, a first transport guide rib 133a, a pressure adjustment lever 434a, and a first transport roller 136, and is pivotally supported by the image forming apparatus so as to be rotatable.

[0114] The transport guide lock release lever 132a is pivotally supported on the transport guide 131 and is configured to be rotatable relative to the transport guide 131. The transport guide 131 can be opened and closed by gripping the transport guide lock release lever 132a and the first transport guide rib 133a with fingers and operating the transport guide lock release lever 132a in the direction of releasing it.

[0115] On the other hand, pressure adjustment lever 434a is pivotally supported by shaft 134P provided on conveyance guide 131, and is configured to be rotatable relative to conveyance guide 131. Pressure adjustment lever 434a is provided with engagement portion 441a, which engages with engagement shaft 443P provided on the device side when pressure adjustment lever 434a is in the envelope mode position with conveyance guide 131 closed, and is configured to be disengaged when pressure adjustment lever 434a is in the normal mode position. By operating pressure adjustment lever 434a in the direction of disengagement, conveyance guide 131 can be opened and closed.

[0116] In the third embodiment, the jam clearance procedure in the envelope mode is limited to one procedure. As shown in Fig. 16, in the envelope mode, the pressure adjustment lever 434a is in the depressed position (envelope mode), so the pressure adjustment lever 434a is pushed up with a finger and operated in the direction of the pushed-up position to release the pressure adjustment lever 434a.

[0117] Next, as shown in Figure 16, by grasping the transport guide lock release lever 132a and the first transport guide rib 133a with your fingers and operating the transport guide lock release lever 132a in the direction of releasing it, the transport guide 131 can be opened and closed, making it possible to clear jams.

[0118] Even if an attempt is made to open the conveying guide 131 without returning the pressure adjustment lever 434a to its normal position, the engaging portion 441a of the pressure adjustment lever 434a is engaged with the engaging shaft 443P provided on the device side, making it impossible to open the conveying guide 131. This solves the problem of the conventional example in which the pressure adjustment lever 434a comes into contact with the operator's fingers because the conveying guide 131 does not open even when an attempt is made to open it with the pressure adjustment lever 434a pressed down and the pressure adjustment lever 434a does not move to its normal position. [Explanation of symbols]

[0119] 1 Printer unit (main unit) O1 First swing axis O2 2nd swing axis center 2 Joint cover (first movable part) 3. Reading device (first moving part) 3b Placement surface 3b Reading part 4 Automatic paper feeder (first moving part) 4a Conveyor section 11a, 11b First hinge part 12a, 12b Second hinge part 15 Image forming unit 20 Main unit cover 21 Rear cover (second movable part) 22 Front cover 23, 24 Side covers 25K, 25Y, 25M, 25C Cartridge (replacement part) 26K, 26Y, 26M, 26C LED head 27 Upper opening 28 Posterior opening 29 Conveyor belt (first sheet conveying means) 30 Vertical conveying path (second sheet conveying means) 51 Paper tray 52 Paper output tray 131 Transport guide 132a, 132b Transport guide lock release lever 133a, 133b First conveying guide rib 134a, 134b Pressure adjustment lever 135a, 135b Swing lever 136 First conveying roller 137 Second conveying roller 138 Fixing pressure roller 139 Fixing heating roller 140a, 140b Fixing biasing members 232a, 232b Transport guide lock release lever 233a, 233b First conveying guide rib 332a, 332b Transport guide lock release button 341a, 341b Transport guide lock 434a, 434b Pressure adjustment lever 441a, 441b Pressure adjustment lever engagement portion 443P Pressure adjustment lever engagement shaft

Claims

1. An image forming apparatus, a fixing device including a heating roller for heating an unfixed image formed on a sheet and a pressure roller for pressing the sheet between the heating roller and the pressure roller, thereby fixing the unfixed image on the sheet; a housing that houses the fixing device and has a discharge section that discharges the sheet that has passed through the fixing device to the outside of the image forming apparatus; an exterior cover that is provided to be openable and closable relative to the housing and that forms an exterior of the image forming apparatus when closed; a sheet guide member provided inside the outer cover and capable of opening and closing relative to the housing when the outer cover is open, the sheet guide member being movable between a closed position where it is closed to guide the sheet discharged from the discharge section and an open position where it is open to allow an operator to access the fixing device; a lock lever rotatably provided on the sheet guide member and engaging with the housing to lock the sheet guide member in the closed position; an operating lever that is provided on the sheet guide member vertically below the lock lever and that moves the pressure roller from a first pressing position where it presses the heat roller with a first pressing force to a second pressing position where it presses the heat roller with a second pressing force that is smaller than the first pressing force, the operating lever rotating relative to the sheet guide member and taking a first position when the pressure roller is at the first pressing position and a second position when the pressure roller is at the second pressing position; an image forming apparatus, characterized in that the lock lever and the operating lever are provided on the sheet guide member so that the direction of the rotation axis of the lock lever intersects with the direction of the rotation axis of the operating lever;

2. a support member that rotatably supports the pressure roller and swings around one end thereof; a spring provided on the other end side of the support member and applying a force to the support member so as to press the pressure roller against the heating roller; 2. The image forming apparatus according to claim 1, wherein the pressure roller moves from the first pressing position to the second pressing position when the operating lever presses the support member against the restoring force of the spring.

3. 3. The image forming apparatus according to claim 2, wherein the pressure roller is positioned vertically below the heat roller.

Images