JP2020117402A - Image formation apparatus - Google Patents

Abstract

To improve the workability of attachment/detachment of a sheet discharge roller and a roller holder of a sheet discharge part while achieving space-saving of the apparatus by preventing conveyance failure of a sheet.SOLUTION: An image formation apparatus comprises a sheet discharge part 1300 which has at least one pair of a sheet discharge roller 1301 and a sheet discharge roller 1401 for discharging a sheet P formed with an image by an image formation part. The sheet discharge roller 1301 on the driven side is arranged so as to be attachable/detachable with respect to the sheet discharge part 1300 via a roller holder 1302. The sheet discharge roller 1301 includes a leading shaft 1503 being a rotation shaft, and plural rollers 1501 and rollers 1502 integrated with the leading shaft 1503. The sheet discharge part 1300 includes a relay unit 1701 and a post-processor 1900 in an attachable/detachable manner. The sheet discharge roller pair 13 is configured so that the sheet discharge roller 1301 on the driven side is replaced with different sheet discharge rollers in accordance with such configurations that the relay unit 1701 and post-processor 1900 are attached and the relay unit and post-processor are detached.SELECTED DRAWING: Figure 18

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine and a printer, and more particularly to an image forming apparatus in which a relay unit for processing sheets discharged from the image forming apparatus and a post-processing device can be mounted.

Generally, in an image forming apparatus such as a copying machine or a printer, when a sheet on which an image is formed is discharged to a sheet discharge tray, the sheet is attached to the sheet and discharged. This waist is also called corrugation, and is formed in a corrugated shape on the paper, and the top of this corrugation extends in the sheet conveying direction (discharging direction) to form a line. In this way, the user can discharge the paper to the paper discharge tray by removing the curl and curl of the paper by discharging the paper while keeping it lean.

However, in the conventional corrugation applying/non-applying switching means, when various types of post-processing devices are attached to the main body sheet discharging part, a conveyance failure may occur in the delivery part or the inside of the post-processing device. For example, when the transport path is bent in the post-processing apparatus, when the corrugated paper enters, the waisted paper does not follow the transport path and a transport failure occurs.

As a configuration that makes the stiffness of the paper variable, it has already been possible to switch the presence/absence of the stiffness by changing the configuration that gives the corrugation individually in the direction intersecting the paper surface, and the configuration that makes the stiffness of the stiffness variable. It is known (for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2004-242242 discloses a plurality of waist forming members provided at predetermined intervals in a direction orthogonal to the paper conveying direction for the purpose of changing the position and the strength of supporting the discharged paper. In the double-sided image forming process for forming images on both sides of the paper, the first surface of the image is formed on the first surface by a plurality of driving means for individually moving the supporting member of the paper in a direction intersecting the paper surface of the paper discharged by the discharge roll. When a part of the paper on which the sheet is formed is discharged to the outside of the machine by the discharge roll, the plurality of waist attachment members are selectively moved from the retracted position to the waist attachment position under the first condition, and the second surface When the paper on which the image is formed is discharged to the outside of the machine by the discharge roll, the plurality of waist attachment members are selectively moved from the retracted position to the waist attachment position under the second condition different from the first condition. A configuration of an image forming apparatus including a control unit that controls the plurality of driving units so as to move is disclosed.

As described above, in the image forming apparatus described in Patent Document 1, when the images are formed on both sides of the sheet, the support member is formed depending on whether the image is formed on the first surface or the second surface. By selectively moving the position of, it is possible to change the position and strength at which the discharged paper is supported.

However, in the configuration in which the corrugation imparting member is automatically advanced and retracted, it is possible to change the presence/absence of waist attachment, but the configuration becomes complicated and the space required for installing the corrugation imparting member becomes large, resulting in cost reduction. There was a problem of uploading.

Further, as a configuration in which the presence/absence of waist attachment is made variable, instead of advancing/retreating the corrugation imparting member, a configuration in which the tubular member is attached/detached to/from the recess provided in the roller shaft on the inner diameter side of the kick-out portion for attachment It is disclosed (for example, Patent Document 2). According to the configuration described in Patent Document 2, it is possible to switch between wearing and not wearing by simply attaching and detaching the tubular member, and it is not necessary to secure a large space for the corrugation providing member in the image forming apparatus.

However, in the configuration described in Patent Document 2, the roller shaft is fixed to the main body, and when the tubular member is attached to or detached from the recess, the retaining ring previously attached to the roller shaft is removed for each kicking portion, It is necessary to slide the tubular member along the roller shaft to position the tubular member, and then attach the retaining ring to the roller shaft, which makes it difficult to attach and detach the tubular member.

The present invention has been made in order to solve such a problem, and prevents the defective conveyance of the sheet by changing the loosening condition according to the sheet conveyance path after the sheet discharge unit, and realizes the space saving of the apparatus. At the same time, it is an object of the present invention to improve the workability of attaching/detaching the discharge roller and the roller holder of the discharge unit.

In order to achieve the above object, an image forming apparatus according to the present invention transfers a image formed by an image forming unit onto a sheet and then fixes the image onto the sheet. An image forming apparatus having setting means for setting the type of the sheet, the upstream side of the branch member that switches the downstream side of the fixing device and the path for discharging the sheet to the outside of the image forming apparatus and the double-sided reversing path. And a guide member that guides the sheet discharged from the pair of conveyance auxiliary rollers immediately after the pair of conveyance auxiliary rollers, the guide member comes into contact with the sheet, and the pair of conveyance auxiliary rollers are provided. To a first position where the angle formed between the sheet discharged from the sheet and the guide member is changed, and to a second position where the angle formed between the sheet discharged from the conveyance auxiliary roller pair and the guide member is not changed. A movable driving unit is provided, and the guide member is arranged at the second position regardless of the type of the sheet during double-sided printing on the sheet.

According to the present invention, it is possible to prevent a defective conveyance of a sheet by changing the loosening condition according to the conveyance path of the sheet after the sheet discharge section and realize the space saving of the device, and The workability of attaching and detaching the roller holder can be improved.

1 is a sectional view showing a schematic configuration of an image forming apparatus according to a first embodiment of the present invention. FIG. 3 is a perspective view showing an image reading unit of the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of a curl correcting mechanism and a fixing device of the image forming apparatus according to the first exemplary embodiment of the present invention. FIG. 3 is a perspective view of a paper discharge unit of the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of the sheet discharge unit of the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is a front view of a paper discharge roller of the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of a paper discharge roller of the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is a front view of a paper discharge roller of the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of a paper discharge roller of the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is a diagram showing the assembly of the paper discharge roller to the roller holder of the image forming apparatus according to the first exemplary embodiment of the present invention. FIG. 3 is a diagram showing how the sheet discharge roller of the image forming apparatus according to the first exemplary embodiment of the present invention is attached to the sheet discharge unit. FIG. 3 is a diagram showing the assembly of the paper discharge roller to the roller holder of the image forming apparatus according to the first exemplary embodiment of the present invention. FIG. 3 is a diagram showing the assembly of the paper discharge roller to the roller holder of the image forming apparatus according to the first exemplary embodiment of the present invention. FIG. 3 is a diagram showing the assembly of the paper discharge roller to the roller holder of the image forming apparatus according to the first exemplary embodiment of the present invention. FIG. 3 is a diagram showing the assembly of the paper discharge roller to the roller holder of the image forming apparatus according to the first exemplary embodiment of the present invention. FIG. 3 is a cross-sectional view of a state in which a relay unit is mounted on the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is a perspective view of a state in which a relay unit and a post-processing device are mounted on the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of a state in which a relay unit and a post-processing device are mounted on the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of a state in which a paper discharge tray is provided in the image forming apparatus according to the first embodiment of the present invention. It is a figure explaining the position of the guide member in the image forming apparatus which concerns on the 2nd Embodiment of this invention. It is a figure explaining the position of the guide member in the image forming apparatus which concerns on the 2nd Embodiment of this invention. It is a figure explaining the position of a guide member and a branch member in each operation mode in an image forming device concerning a 2nd embodiment of the present invention. It is a figure which shows the pressurization side separation conveyance member of the image forming apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the positional relationship of the guide member and conveyance auxiliary roller pair of the image forming apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the relationship of the drive means and guide member of the image forming apparatus which concerns on the 2nd Embodiment of this invention. FIG. 8 is a schematic diagram showing a positional relationship between a guide member and a drive roller of the image forming apparatus according to the second exemplary embodiment of the present invention. It is a figure which shows the relationship of the drive means and guide member of the image forming apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the relationship of the drive means and guide member of the image forming apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the positional relationship of the guide member and the branch member of the image forming apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the position of the humidity detection means of the image forming apparatus which concerns on the 3rd Embodiment of this invention. It is a figure which shows the position of the humidity detection means of the image forming apparatus which concerns on the 3rd Embodiment of this invention. It is a schematic block diagram which shows the control structure of the image forming apparatus which concerns on the 3rd Embodiment of this invention. FIG. 13 is a diagram comparing the relationship between the on-off state of the decurler depending on the paper thickness and humidity of the image forming apparatus according to the third exemplary embodiment of the present invention and another image forming apparatus of the present situation. FIG. 11 is a process flow chart showing on/off control of a decurler of an image forming apparatus according to a third embodiment of the present invention.

First, with reference to FIG. 1, the overall configuration and operation of an image forming apparatus according to an embodiment of the present invention will be described.

(First embodiment)
The image forming apparatus 1 shown in FIG. 1 is a color laser printer, and four image forming units 4Y, 4M, 4C, and 4K are provided in the center of the apparatus main body, and an image reading unit 40 is provided above the apparatus main body. Is provided. The image forming unit A that forms an image on the paper P in the image forming apparatus 1 includes an image forming unit 4. The image forming units 4Y, 4M, 4C, and 4K store toners and developers of different colors of yellow (Y), magenta (M), cyan (C), and black (K) corresponding to the color separation components of the color image. It has the same structure except that it is housed.

Specifically, each of the image forming units 4Y, 4M, 4C, and 4K includes a drum-shaped photoconductor 5 as a latent image carrier, a charging device 6 that charges the surface of the photoconductor 5, and a surface of the photoconductor 5. A developing device 7 for supplying toner, a cleaning device 8 for cleaning the surface of the photoconductor 5 and the like are provided. In FIG. 1, reference numerals are given only to the photoconductor 5, the charging device 6, the developing device 7, and the cleaning device 8 included in the black image forming unit 4K, and in the other image forming units 4Y, 4M, and 4C. The reference numerals are omitted.

An exposure device 9 that exposes the surface of the photoconductor 5 is disposed below the image forming units 4Y, 4M, 4C, and 4K. The exposure device 9 has a light source, a polygon mirror, an f-θ lens, a reflection mirror, etc., and irradiates the surface of each photoconductor 5 with laser light based on image data.

The transfer device 3 is arranged above the image forming units 4Y, 4M, 4C, and 4K. The transfer device 3 includes an intermediate transfer belt 30 as an intermediate transfer member, four primary transfer rollers 31 as a primary transfer unit, a secondary transfer roller 36 as a secondary transfer unit, and a secondary transfer backup roller 32. The cleaning backup roller 33, the tension roller 34, and the belt cleaning device 35 are provided.

The intermediate transfer belt 30 is an endless belt and is stretched around a secondary transfer backup roller 32, a cleaning backup roller 33, and a tension roller 34. Here, by rotating the secondary transfer backup roller 32, the intermediate transfer belt 30 is circulated (rotated) in the direction shown by the arrow in the figure.

Each of the four primary transfer rollers 31 sandwiches the intermediate transfer belt 30 with each photoconductor 5 to form a primary transfer nip. A power source is connected to each primary transfer roller 31, and a predetermined direct current voltage (DC) and/or alternating current voltage (AC) is applied to each primary transfer roller 31.

The secondary transfer roller 36 sandwiches the intermediate transfer belt 30 with the secondary transfer backup roller 32 to form a secondary transfer nip. Further, like the primary transfer roller 31, a power source is also connected to the secondary transfer roller 36, and a predetermined DC voltage (DC) and/or AC voltage (AC) is applied to the secondary transfer roller 36. It is like this.

The belt cleaning device 35 has a cleaning brush and a cleaning blade which are arranged so as to contact the intermediate transfer belt 30. The waste toner collected by the belt cleaning device 35 is stored in the waste toner container via the waste toner transfer hose.

A bottle container 2 is provided in the upper part of the image forming apparatus main body, and four toner bottles 2Y, 2M, 2C, and 2K containing replenishment toner are detachably attached to the bottle container 2. ing. Toner is replenished to each developing device 7 from each toner bottle 2Y, 2M, 2C, 2K via a replenishing path provided between each toner bottle 2Y, 2M, 2C, 2K and each developing device 7.

On the other hand, in the lower part of the main body of the image forming apparatus, there are provided a paper feed tray 10 that contains paper P as a recording medium, a paper feed roller 11 that carries out the paper P from the paper feed tray 10, and the like. The recording medium includes thick paper, postcards, envelopes, thin papers, coated papers (coated papers, art papers, etc.), tracing papers, OHP sheets, etc. in addition to plain papers. Further, a manual paper feeding mechanism may be provided.

Inside the main body of the image forming apparatus, there is provided a conveyance path R for passing the paper P from the paper feed tray 10 through the secondary transfer nip and ejecting it to the outside of the apparatus. In the transport path R, a pair of registration rollers 12 as timing rollers for timing the transport timing and transporting the paper P to the secondary transfer nip are disposed upstream of the position of the secondary transfer roller 36 in the paper transport direction. ing.

Further, a fixing device 20 for fixing the unfixed image transferred to the sheet P is disposed downstream of the position of the secondary transfer roller 36 in the sheet conveying direction. Further, a paper discharge roller pair 13 for discharging the paper P to the outside of the apparatus is provided on the downstream side of the fixing device 20 in the paper carrying direction of the carrying path R. Further, a paper discharge tray 14 for stacking the paper P discharged to the outside of the apparatus is provided on the upper surface of the apparatus main body. The paper discharge roller pair 13 constitutes a pair of paper discharge rollers according to the present invention.

A relay unit 1701 and a post-processing device 1900, which will be described later, may be mounted on the image forming apparatus 1 (see FIG. 17).

Subsequently, the basic operation of the printer according to the present embodiment will be described with reference to FIG.

When the image forming operation is started, the photoconductors 5 in the image forming units 4Y, 4M, 4C, and 4K are rotationally driven in the clockwise direction in the figure, and the surface of each photoconductor 5 has a predetermined polarity by the charging device 6. It is uniformly charged. The surface of each charged photoconductor 5 is irradiated with laser light from the exposure device 9, and an electrostatic latent image is formed on the surface of each photoconductor 5. At this time, the image information exposed on each photoconductor 5 is monochromatic image information in which a desired full-color image is separated into color information of yellow, magenta, cyan, and black. By supplying toner to each electrostatic latent image formed on each photoconductor 5 by each developing device 7, the electrostatic latent image is visualized as a toner image (visualized). ..

Further, when the image forming operation is started, the secondary transfer backup roller 32 is rotationally driven counterclockwise in the figure, and the intermediate transfer belt 30 is circulated in the direction shown by the arrow in the figure. Further, by applying a constant voltage or a constant current controlled voltage having a polarity opposite to the charging polarity of the toner to each primary transfer roller 31, a primary transfer nip between each primary transfer roller 31 and each photoconductor 5 is applied. A transfer electric field is formed at.

After that, when the toner images of the respective colors on the photoconductors 5 reach the primary transfer nip as the photoconductors 5 rotate, the toner images on the photoconductors 5 are formed by the transfer electric field formed in the primary transfer nip. Are sequentially superimposed and transferred onto the intermediate transfer belt 30. Thus, a full-color toner image is carried on the surface of the intermediate transfer belt 30. Further, the toner on each photoconductor 5 that could not be transferred to the intermediate transfer belt 30 is removed by the cleaning device 8. Then, the surface of each photoconductor 5 is neutralized by the static eliminator, and the surface potential is initialized.

At the lower part of the main body of the image forming apparatus 1, the paper feed roller 11 starts to rotate and the paper P is sent out from the paper feed tray 10 to the transport path R. The conveyance of the sheet P sent to the conveyance path R is temporarily stopped by the registration rollers 12.

After that, the registration roller 12 starts to rotate at a predetermined timing, and the paper P is conveyed to the secondary transfer nip at the timing when the toner image on the intermediate transfer belt 30 reaches the secondary transfer nip. At this time, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the intermediate transfer belt 30 is applied to the secondary transfer roller 36, whereby a transfer electric field is formed in the secondary transfer nip. .. Then, due to this transfer electric field, the toner images on the intermediate transfer belt 30 are collectively transferred onto the paper P. Further, at this time, the residual toner on the intermediate transfer belt 30 that could not be completely transferred to the paper P is removed by the belt cleaning device 35, and is conveyed to the waste toner container.

After that, the paper P is conveyed to the fixing device 20, and the toner image on the paper P is fixed on the paper P by the fixing device 20. The sheet P conveyed from the fixing device is guided in the discharging direction and the re-feeding direction via the branch member 15 for switching the path for discharging the sheet P to the outside of the apparatus and the double-sided reverse path.

In the single-sided sheet passing mode, the branching member 15 is opened, and the sheet P discharged to the outside of the apparatus provided on the upper surface of the apparatus main body is stacked by the sheet discharge roller pair 13 for discharging. The sheet is discharged to the sheet discharge tray 14.

In the double-sided sheet passing mode, the branching member is closed in the direction of the arrow so that the sheet P after the first side fixing is guided to the double sided reversing path. The sheet P guided to the double-sided reversing path is switched back by the pair of reversing rollers 16, is conveyed to the double-sided unit 17, is conveyed again to the pair of registration rollers 12, and is re-fed, so that the first surface Similarly, the second surface image is printed on the back surface of the paper P. Then, the paper P is discharged to the outside of the apparatus by the paper discharge roller pair 13 and is stacked on the paper discharge tray 14.

The above description is for the image forming operation when forming a full-color image on a sheet, but a single-color image is formed using any one of the four image forming units 4Y, 4M, 4C, and 4K. It is also possible to form a two-color or three-color image by using two or three image forming units.

As shown in FIG. 1, the image reading unit 40 is located above the main body of the image forming apparatus 1. As shown in FIG. 2, the image reading unit 40 includes a first contact glass 45 positioned on the conveyance path of the paper P, a second contact glass 46 on which the paper P can be placed, and abutting and positioning of one side of the paper P. And an abutting member 47a capable of Further, the image forming apparatus 1 has an operation unit 150 installed on the front side of the upper part.

The operation unit 150 has a print key 151, an operation display unit 152, and the like. When the print key 151 is pressed, the operation unit 150 requests the image forming apparatus 1 to start a copying operation. The operation display unit 152 is configured to operate and display various information related to printing and the like.

The curl correcting mechanism and the fixing device will be described in detail with reference to FIG. FIG. 3 is a sectional view of the curl correcting mechanism and the fixing device.

As shown in FIG. 3, the fixing device 20 is used for melting and penetrating the transferred toner image carried on the paper P by heat and pressure to fix the toner image, and as shown in FIG. The fixing belt 21 having a rotatable flexibility is provided.

The fixing device 20 includes, in addition to the fixing belt 21, a pressure roller that is an opposed rotating body that forms a nip portion N by applying pressure between the fixing belt 21 and the fixing belt 21 in a contact state with the fixing belt 21. 22 is provided. Inside the fixing belt 21, a heater 23 having a plurality of halogen lamps 23 a and 23 b for heating the fixing belt 21 at a position other than the nip portion N is provided.

Inside the fixing belt 21, a nip forming member 24, which is a base member for forming a nip disposed inside the fixing belt 21, a stay 25 supporting the nip forming member 24, and light emitted from the heater 23. A reflecting member 26 that reflects the light to the fixing belt 21 is provided. The nip forming member 24, which is the base member for forming the nip, has a sliding sheet (low friction sheet) around the base pad.

In the illustrated nip forming member 24, the shape of the nip portion N is flat, but the shape is not limited to this. For example, when it is formed in a concave shape along the circumferential surface of the pressure roller 22, the leading edge of the paper P passing through the nip portion N approaches the pressure roller 22 side, so that the separability from the fixing belt 21 is improved. There are advantages. The temperature of the fixing belt 21 is detected by the temperature sensor 27 provided on the side where the paper P enters the nip portion, and is used for the feedback process of the heater 23. Note that, in FIG. 3, the arrow F indicates the conveyance direction of the paper P.

The fixing belt 21 is a thin and flexible sleeve-shaped endless belt, and is composed of a base material and a release layer positioned on the surface of the base material. A metal material such as nickel or SUS or a resin material such as polyimide is used for the base material. Further, for the release layer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) or polytetrafluoroethylene (PTFE) having a releasing property to the toner is used.

The pressure roller 22 includes a cored bar 22a, an elastic layer 22b provided on the surface of the cored bar 22a and made of foamable silicone rubber, silicone rubber, fluororubber, or the like, and PFA provided on the surface of the elastic layer 22b. The release layer 22c is made of PTFE or the like. The pressure roller 22 is pressed against the fixing belt 21 by a pressure means (not shown) and is in contact with the fixing belt 21, and is in contact with the nip forming member 24 as a base member.

At the location where the pressure roller 22 and the fixing belt 21 come into contact, the elastic layer 22b of the pressure roller 22 is crushed, so that pressure is applied between the pressure roller 22 and the fixing belt 21 so that the nip forming member 24 has a predetermined width. The nip portion N is secured.

The pressure roller 22 is configured to be rotationally driven by a drive source such as a motor (not shown) provided in the main body of the image forming apparatus. When the pressure roller 22 is rotationally driven, the driving force is transmitted to the fixing belt 21 at the nip portion N, and the fixing belt 21 is driven to rotate.

In the configuration shown in FIG. 3, the pressure roller 22 is a solid roller, but it may be a hollow roller. In that case, a heating source such as a halogen heater using radiant heat can be provided inside the pressure roller 22. Further, when the elastic layer 22b is not provided, the heat capacity becomes small and the fixability is improved, but when the unfixed toner is crushed and fixed, the minute unevenness on the belt surface is transferred to the image and the solid portion of the image becomes glossy. Unevenness may occur. To prevent this, it is desirable to provide an elastic layer having a thickness of 100 μm or more. Aluminum, iron, stainless steel, or the like can be selected as the pipe-shaped metal used for the hollow roller.

When a heat source is provided in the pressure roller 22, a heat insulating layer is provided on the surface of the support or a heat ray reflecting surface is provided by a mirror surface treatment in order to prevent the support from being heated by radiant heat from the heat source. Is desirable. In this case, the heat source is not limited to the halogen heater described above, but an IH heater, a resistance heating element, or a carbon heater can be used.

On the paper exit side of the fixing device 20, there is provided a separation/conveyance mechanism that separates the paper P that has passed through the nip portion near the nip portion and guides the paper P toward the paper ejection unit 1300 in the ejection direction. The separating/conveying mechanism has a belt-side separating/conveying member 201 having a tip close to the fixing belt 21 on the downstream side in the conveying direction of the paper P passing through the nip portion, and an adder having a tip close to the pressure roller 22 side. And a pressure side separation/conveyance member 202.

The belt-side separating/conveying member 201 is provided for peeling the leading end of the paper P, which tends to stick to and stick to the fixing belt 21, from the fixing belt 21. For this reason, a plate-shaped metal is provided so that the adhered paper P can be positioned at a close position where it can be lifted from the surface of the fixing belt 21.

The pressurizing-side separating/conveying member 202 is made of a resin molded product, and a supporting rod 202A provided in a part thereof is rotatably supported on the housing side so that the swinging end facing the pressurizing roller 22 is moved. The pressure roller 22 can be swung so that it can come into contact with and separate from the pressure roller 22. The pressure-side separating/conveying member 202 swings with respect to the pressure roller 22 to swing away from the pressure roller 22 when the jammed paper P is removed from the nip N, for example. A space for inserting the hand into the part N can be created. As a result, the paper P can be accessed.

A transport auxiliary roller pair 230 including a drive roller 204 supported by the pressure side separation transport member 202 and a driven roller 203 supported by a holder 207 is disposed downstream of the separation transport member.

The driving roller 204 is made of a core metal and a solid rubber material 204b having a high friction coefficient such as silicon, EPDM, urethane, or fluororubber provided on the surface of the core metal so as to obtain a sheet conveying force. The driven roller 203 has a structure in which a low-μ tube (thickness 30 to 300 μm) such as PFA, ETFA, or FEP is covered on the surface of a hollow pipe-shaped metal.

The reason why the driven roller 203 is made of a hollow pipe-shaped metal is that the water vapor generated by evaporating from the paper P during fixing adheres to the driven roller side to prevent dew condensation, so that the driven roller 203 has a low heat capacity and is quickly heated by the heat from the fixing. To do so.

The reason why the low-μ tube is arranged on the surface of the driven roller 203 is that the trace amount of toner that cannot be completely melted after fixing and the toner in a semi-molten state are difficult to adhere, and even if they adhere, they do not accumulate. Is. Since the driven roller side conveys the image surface side while always contacting the image surface side, the structure is as described above. On the contrary, the drive roller 204 is in contact with the surface opposite to the image surface side. By pressing the holder holding the driven roller 203 with a spring, the drive roller 204 and the driven roller 203 come into contact with each other to form a nip, and the sheet can be conveyed.

Next, the configuration of the paper discharge unit in the present embodiment will be described with reference to FIGS.

4 and 5 are an external perspective view and a cross-sectional view of the paper discharge unit 1300 of the image forming apparatus 1 according to this embodiment. The paper discharge unit 1300 includes a paper discharge roller pair 13 including a paper discharge roller 1301 and a paper discharge roller 1401, a roller holder 1302, a paper discharge guide plate 1303, and a paper discharge tray 14. The paper discharge roller 1301 and the paper discharge roller 1401 constitute the discharge roller according to the present invention, and the paper discharge roller 1301 constitutes the driven side discharge roller according to the present invention.

The paper P having the toner fixed through the above process is discharged by the paper discharge roller pair 13 to the paper discharge tray 14 in the cylinder.

The paper discharge roller 1401 is a drive-side roller to which power from the motor is transmitted, and is attached to the main body side of the image forming apparatus 1. The paper discharge roller 1301 is pressed by a spring in the direction of the paper discharge roller 1401 and is a driven roller that is entrained with the paper discharge roller 1401 by the nip pressure. Further, the paper discharge roller 1301 is configured to be detachable from the paper discharge guide plate 1303 via the roller holder 1302.

The discharge roller pair 13 will be described with reference to FIGS. 6 to 9. As will be described later, in the present embodiment, the type of the driven-side paper discharge roller 1301 applied to the paper discharge unit 1300 is changed according to the path of the paper P that has passed through the paper discharge unit 1300.

The paper ejection roller 1301 shown in FIGS. 6 and 7 is a paper ejection roller of the type that forms corrugations on the paper P. 6 is a front view of the paper discharge roller 1301, and FIG. 7 is a perspective view thereof.

The paper discharge roller 1301 includes a roller 1501, a roller 1502, a through shaft 1503, and a spring receiving roller 1506. The roller 1501 forms a nip with the roller 1504 of the paper discharge roller 1401. Each of the rollers 1501 and 1502 is a resin made of POM (polyacetal). In this embodiment, four rollers 1501 are provided, but the number of rollers 1501 is not limited to this. The roller 1502 is configured to have a diameter larger than that of the roller 1501 in order to attach the paper P passing through the paper discharge roller pair 13 to the waist. In this embodiment, two rollers 1502 are provided, but the number of rollers 1502 is not limited to this.

The through shaft 1503 serves as a rotation shaft of the paper discharge roller 1301, and the rollers 1501 and 1502 are assembled around the shaft. By assembling a roller 1502 having a large diameter in the vicinity of the roller 1501, a corrugation is formed on the sheet P due to the height difference between the rollers as illustrated.

The spring receiving rollers 1506 are paired on both sides of a part of the rollers 1502 and are attached to the through shaft 1503. In the present embodiment, the spring receiving rollers 1506 are assembled to the two rollers 1502, but the number of spring receiving rollers to be assembled is not limited to this. The spring receiving roller 1506 comes into contact with the spring 1605 provided on the roller holder 1302 and receives the biasing force of the spring 1605.

The paper discharge roller 1401 is composed of a plurality of rollers 1504 and a through shaft 1505. The paper discharge roller 1401 is assembled and fixed to the main body of the image forming apparatus 1. The roller 1504 is provided at a position facing the roller 1501 of the paper discharge roller 1301, and forms a nip with the roller 1501.

Next, with reference to FIGS. 8 and 9, a paper discharge roller 1800 of a type in which corrugation is not formed on the paper P will be described. 8 is a front view of the paper discharge roller 1800, and FIG. 9 is a perspective view thereof.

The paper discharge roller 1800 includes a plurality of rollers 1801 and a through shaft 1802. The roller 1801 forms a nip with the paper discharge roller 1401. In this embodiment, four rollers 1801 are provided, but the number of rollers 1801 is not limited to this. The paper discharge roller 1800 constitutes the discharge roller according to the present invention.

The plurality of rollers 1801 of the paper discharge roller 1800 are constituted by rollers 1801 that are the same as or smaller than the rollers 1504 of the paper discharge roller 1401 that form a nip. For example, the diameter of each roller 1801 may be made substantially equal. Therefore, the height difference between the rollers 1801 does not occur, and the paper P that has passed through the paper discharge roller pair including the paper discharge roller 1401 and the paper discharge roller 1800 is not stiffened.

The through shaft 1802 is the shaft of the paper discharge roller 1800, and the roller 1801 is assembled around the shaft. The paper discharge roller 1401 has the same structure as that shown in FIGS.

The configurations of the discharge roller 1301 and the roller holder 1302 will be described with reference to FIGS. 10 and 11.

FIG. 10 is a diagram illustrating a case where the paper discharge roller 1301 forming a corrugation is assembled to the roller holder 1302. The paper discharge roller 1301 is assembled to the roller holder 1302 together with a pressure spring (not shown) to form a paper discharge roller group 1603. The paper discharge roller 1301 is held by the roller holder 1302. As shown in FIG. 4, the discharge roller group 1603 is detachably attached to the discharge guide plate 1303 on the main body side of the image forming apparatus 1.

The roller holder 1302 has a protrusion 1601, a lever 1602, a bearing hook 1604, and a spring 1605 (see FIG. 12). The protrusion 1601 is adapted to engage with the paper ejection guide plate 1303. The lever portion 1602 is adapted to fix the discharge roller group 1603 to the discharge portion 1300 by inserting it into an engaging portion 1303b provided at the other end of the discharge guide plate 1303.

The bearing hook 1604 engages with the through shaft 1503 of the paper discharge roller 1301 when the paper discharge roller 1301 is assembled to the roller holder 1302. The spring 1605 comes into contact with the spring receiving roller 1506 and applies a biasing force to the paper discharge roller 1301 when the paper discharge roller 1301 is assembled to the roller holder 1302. The roller holder 1302 is a resin made of POM (polyacetal).

As shown in FIG. 11, the protrusion 1601 is inserted into the engaging portion 1303a provided at one end of the paper ejection guide plate 1303, and then the lever portion 1602 is inserted into the engaging portion 1303b provided at the other end of the paper ejection guide plate 1303. The paper ejection roller group 1603 is fixed to the paper ejection unit 1300 by inserting.

The procedure for forming the paper discharge roller 1301 will be described below. First, the rollers 1501 and 1502 are attached to the through shaft 1503 by press fitting, the spring receiving roller 1506 is assembled to the through shaft 1503 with a slight backlash, and the rollers 1501 and 1502 are press fit into the through shaft 1503 and then The spring receiving rollers 1506 on both sides of the 1502 are thrust by a pair. As a result, the positional relationship among the rollers 1501 and 1502 and the spring receiving roller 1506 is fixed with respect to the through shaft 1503. The paper discharge roller 1301 is an integrated type component, and can be easily attached to and detached from the roller holder 1302. It is also possible to prepare discharge rollers having different shapes of the rollers 1501 and 1502, and attach/detach to/from another discharge roller according to the necessity of corrugation.

A procedure for assembling the discharge roller 1301 to the roller holder 1302 will be described with reference to FIGS. 12 and 13. 12 and 13 are views of the discharge roller 1301 and the roller holder 1302 viewed from a side different from that of FIG. From the state shown in FIG. 12, the spring receiving roller 1506 of the paper discharge roller 1301 is brought into contact with the spring 1605 of the roller holder 1302 and pushed in the direction of the arrow in the figure. The through shaft 1503 is engaged with the bearing hook 1604 by being pushed in to a position where the through shaft 1503 engages with the bearing hook 1604. When removing the paper discharge roller 1301, the above procedure may be reversed.

14 and 15 are views for explaining a case where the paper discharge roller 1800 that does not form corrugation is assembled to the roller holder 1302. The assembling method is the same as that shown in FIGS.

FIG. 16 shows a state in which a paper discharge roller 1301 capable of corrugation formation is assembled and a relay unit 1701 is mounted in the body barrel. The relay unit 1701 is configured to branch the paper P ejected from the paper ejection roller pair 13 into the in-body ejection section 1704 and a conveyance path 1705 to the subsequent post-processing apparatus 1900. The relay unit 1701 is attachable to and detachable from the paper output unit 1300.

FIG. 17 shows a state in which the relay unit 1701 and the post-processing device 1900 are attached to the image forming apparatus. The relay unit 1701 is configured to convey the paper discharged from the paper discharge unit 1300 to the subsequent post-processing apparatus 1900. The post-processing device 1900 is configured to perform various types of post-processing on the sheet conveyed via the relay unit 1701. The various post-processes referred to herein are, for example, edge-binding process, center-fold process, and the like.

FIG. 18 is a cross-sectional view showing a sheet conveyance path of the image forming apparatus 1 to which the relay unit 1701 and the post-processing apparatus 1900 shown in FIG. 17 are attached. A transport path 1703 in the relay unit 1701 indicated by an arrow in FIG. 18 is a path for sending the toner-fixed paper P to the relay unit 1701 via the paper discharge roller pair 13. Since there is a transport guide plate (not shown) above the relay unit 1701 at the time of sheet reversal, a large space is provided above the in-body discharge section 1704 in order to improve the number of sheet stacks and user operability when removing sheets. Is desirable. Therefore, the transport guide plate 1702 of the relay unit 1701 is configured to incline vertically downward, and the transport path 1703 includes a route inclining vertically downward.

At this time, the leading edge of the sheet of paper P that has passed through the pair of discharge rollers 13 has a large contact angle with the transport guide plate 1702, and further, when corrugation is formed on the sheet of paper P, the sheet of paper P is stiff, so that transport is defective. There is a problem that is likely to occur.

In order to avoid the above-mentioned problems, in the paper discharge unit 1300 of the image forming apparatus 1 shown in FIG. 18, a paper discharge roller 1800 that does not form corrugation is used. As a result, corrugation is not formed on the sheet P, and it is possible to suppress conveyance failure due to the stiffness of the sheet P.

FIG. 19 is a diagram for explaining a case where the sheet discharge tray 14 is provided in the body without using the post-processing apparatus 1900 and the relay unit 1701 and a case where the conveyance path of the sheet P discharged from the sheet discharge unit 1300 is different from the case shown in FIG. Is.

As shown in FIG. 19, the transport path 1706 for the paper P draws a smooth curve, and the paper P is discharged from the paper discharge unit 1300 onto the paper discharge tray 14. Unlike the case shown in FIG. 7, the conveyance path 1706 for the sheet P does not bend sharply, so even if the sheet P has a stiffness, the conveyance failure due to the stiffness does not occur.

Therefore, in the paper discharge unit 1300 of the image forming apparatus 1 shown in FIG. 19, the paper discharge roller 1301 that forms corrugations can be used to remove the curl and curl of the paper, and the conveyance failure due to the stiffness can be eliminated. Does not occur. In this way, the paper ejection roller can be replaced with an appropriate type according to the path of the paper P ejected from the paper ejection unit 1300. In the present embodiment, two types of paper discharge rollers, the paper discharge roller 1301 and the paper discharge roller 1800, are shown, but the types of paper discharge rollers are not limited to these and may be other types.

As described above, in the image forming apparatus 1 according to the present exemplary embodiment, the paper discharge roller 1301 is detachably arranged on the paper discharge unit 1300 via the roller holder 1302, and the paper discharge roller 1301 includes the through shaft 1503 and the roller 1501. And the roller 1502 are integrally configured. Further, the relay unit 1701 can be attached to and detached from the paper discharge unit 1300, and the paper discharge roller 1301, the paper discharge roller 1800, and the roller holder 1302 can be replaced according to the path of the paper P discharged from the paper discharge unit. Has been done.

With this configuration, it is possible to easily change the waist forming condition of the paper discharge roller, and the paper discharging roller 1301 and the paper discharge roller can be adjusted to the waist forming condition according to whether the relay unit 1701 and the post-processing device 1900 are attached. This can be easily performed by partially replacing 1800. Further, by selecting an appropriate waisting condition, it is possible to prevent the defective conveyance of the paper P after the paper discharge unit 1300.

Further, since the post-processing apparatus 1900 is attached and detached very rarely when assembled at the time of installing the main body of the image forming apparatus 1, the post-processing apparatus 1900 can sufficiently perform the function even if the paper discharge roller 1301 or the paper discharge roller 1800 is replaceable, and is automatically operated. There is no need for a switching configuration. Therefore, no space is required to move the paper discharge roller forward and backward, which contributes to space saving and cost reduction.

In addition, since it is possible to change the waist attachment condition by exchanging the discharge rollers, it is possible to improve the degree of freedom in layout of the transport path of the relay unit 1701.

Further, since the paper discharge roller 1301 and the paper discharge roller 1800 are integrated with the roller and the through shaft, and the mounting condition of the paper P can be changed by exchanging each paper discharge roller, the workability of attaching and detaching the paper discharge roller and the roller holder is improved. Can be improved.

Further, the image forming apparatus 1 may include a paper discharge tray 14 from which the paper P is discharged from the paper discharge unit 1300.

Further, the relay unit 1701 may be mounted on the paper output unit 1300, and the post-processing apparatus 1900 may be mounted on the relay unit 1701. With this configuration, the sheet P discharged from the sheet discharge unit 1300 can be subjected to various post-processing such as edge binding processing and center folding processing.

Further, the transport path of the paper P in the relay unit 1701 may include a path 1705 that is inclined downward in the vertical direction. With this configuration, the upper space of the in-body discharging unit 1704 can be widened, and the number of sheets stacked and the user operability when removing sheets can be improved.

Further, the plurality of rollers included in the paper discharge roller 1301 may be formed of rollers having substantially the same diameter. With this configuration, since the sheet P passing through the sheet discharge unit 1300 is not stiffened by the sheet discharge rollers 1301, it can be applied when the sheet P does not need to be stiffened.

Further, the plurality of rollers of the paper discharge roller 1301 may be composed of rollers having different diameters. With this configuration, since the paper P passing through the paper discharge unit 1300 is provided with the support rollers 1301 for supporting the paper P, it can be applied when the support for the paper P is required.

In the first embodiment, the configuration of the image forming apparatus that changes the garment forming condition according to the path of the paper discharged from the paper discharge unit is shown. However, it is generally considered that the curl of the paper occurs in the fixing device and the curl is corrected immediately after the fixing.

More specifically, the fixing device used in the electrophotographic image forming apparatus forms a toner image on a sheet by heating and pressing the nip portion. At this time, due to the temperature difference between the heating side and the pressurizing side, the moisture evaporation due to heating is biased, so that the paper is curled. The curled paper causes a conveyance failure due to being caught in a conveyance path, a delivery portion around the finisher, and the like, and also causes a paper misalignment on the discharge tray.

As a technique corresponding to this, a decurler means for correcting the curl of the paper is already known. However, in the conventional decurling means, since the curling is always forcibly applied in the opposite direction by the guide member, there are the following three problems in the case of passing thick paper.

(1) In the fixing device, since the back curl in which the sheet curls on the back surface does not occur, when the guide plate is always set in a position where the curl is applied in the opposite direction, the guide plate reverses and the face curls in reverse. (2) Since the contact force between the guide plate and the paper is strong, the guide member causes damage (scratches) on the back surface of the paper/wear of the guide member. (3) Since the paper has high rigidity, when the tip comes out of the pair of rollers and the tip comes into contact with the guide member, the tip is bent and the like, which makes it difficult to stabilize the conveyance.

For example, in Japanese Patent Laid-Open Publication No. 2004-242242, in order to correct the side curl generated by the temperature difference between the center and the end of the fixing nip, the protrusion is stored when the temperature difference between the center and the end of the fixing nip disappears with the passage of time. Then, the configuration of releasing the correction of the side curl is disclosed.

With the configuration described in Patent Document 3, it is possible to correct the curl and cancel the correction of the curl. However, what can be corrected is limited to side curl, and as described above, when curling is applied in reverse, damage (scratch) to the back surface of thick paper / wear of guide member, tip contact with guide member However, the problem that it is difficult to stabilize the transportation due to bending of the tip has not been solved.

The image forming apparatus according to the second embodiment described below is made in order to solve the above-mentioned problem, and it is appropriate to turn on/off the decurling unit according to the type of paper and whether or not the paper discharge section has a ridge. The purpose of this setting is to prevent conveyance problems due to decals.

(Second embodiment)
The image forming apparatus according to the second embodiment will be described below.

In the image forming apparatus according to the second embodiment, the same components as those in the first embodiment are designated by the same reference numerals as those in the first embodiment shown in FIGS. 1 to 19. Only the differences will be described in detail.

The overall configuration of the image forming apparatus according to the second embodiment is the same as that of the image forming apparatus 1 according to the first embodiment shown in FIG.

The position of the guide member 205 will be described with reference to FIGS. A movable guide member 205 for guiding the paper P ejected from the conveyance auxiliary roller pair 230 is provided immediately downstream of the conveyance auxiliary roller pair 230, and the first position shown in FIG. 20 and FIG. It is configured to be movable in two stages of a second position (described later) shown in.

When the guide member 205 is arranged at the position shown in FIG. 20, in the direction of the paper P discharged from the conveyance auxiliary roller pair 230 (a direction perpendicular to the line connecting the centers of the pair of conveyance auxiliary rollers 230). ) On the other hand, by arranging the sheet at such a position as to close the path, the leading edge of the sheet comes into contact with the guide member 205 at an angle θ, and then the sheet P is pressed against the guide member 205 by the sheet conveying force of the sheet conveying auxiliary roller 230. While being transported.

Finally, by feeding the sheet at the angle of θ1 from the sheet feeding roller nip, the sheet can be bent to the side opposite to the back curl. With such a conveyance path, the paper P ejected from the guide member 205 can be improved in the back curl generated in the fixing nip portion N and can be ejected to the outside of the image forming apparatus 1.

However, since the back surface of the paper and the guide member 205 are positively brought into contact with each other, the conveyance resistance with the guide member 205 is large, and the paper itself is stressed. There is a possibility that a contact mark with the guide member 205 may be generated, or conversely, the guide member 205 itself may be worn.

Further, when the second side of the double-sided sheet-passing mode is used, the surface having the image (first side) comes into contact with the guide member 205, so that image distortion and gloss streak are likely to occur. The reason is that immediately after the fixing unit, while the second image surface is being fixed, the first surface image on the back surface is heated again because the paper passes through the nip portion N, but the outermost surface portion of the toner is not heated when the paper is warm. This is because if it is strongly rubbed, it is likely to be peeled off or the gloss is changed.

On the other hand, when the guide member 205 is arranged at the position shown in FIG. 21, in the direction of the paper discharged from the conveyance auxiliary roller pair 230 (with respect to the line connecting the centers of the rollers of the conveyance auxiliary roller pair 230, In contrast, the guide member 205 is arranged at a retracted position so as not to positively contact the paper P. In this case, the back curl at the time of transporting the sheet cannot be corrected, but the sheet is not stressed, so that the above-mentioned back surface scratch, abrasion, image abrasion, and gloss streak do not occur.

Since it is not possible to achieve both curl correction and image blur prevention at the position of one guide member 205, in the present embodiment, the guide member 205 is driven by a drive unit (described later) according to each sheet passing mode described below. This is made compatible by switching the position of the guide member 205 to the position shown in FIGS. Specifically, the guide member 205 and the branching member 15 are movably arranged as described below to support each sheet passing mode.

First, when the sheet thickness is equal to or smaller than a predetermined value in the single-sided sheet passing mode in which an image is transferred onto only one side of the sheet P, the guide member 205 and the branching member 15 are moved to the positions shown in FIG. At this time, the position of the guide member 205 becomes the first position. This is because when the paper thickness is not large, it is not necessary to consider the friction with the guide member 205 so much, and it is not necessary to convey the paper P to the reverse path.

If the paper thickness is larger than a predetermined value in the single-sided paper passing mode, the guide member 205 and the branch member 15 are moved to the positions shown in FIG. At this time, the position of the guide member 205 becomes the second position. This is because when the paper thickness is large, it is necessary to consider the friction with the guide member 205 so much. In the present embodiment, 160 g/m2 is adopted as the predetermined value of the paper thickness, but it is not necessarily limited to this value, and for example, a larger value is desired when the range of the paper thickness to be subjected to curl correction is widened. May be a predetermined value.

Next, in the double-sided sheet passing mode, the guide member 205 is arranged at the open position on both the first side and the second side of the paper P, and the discharge path for discharging the paper P to the outside of the image forming apparatus 1 and the reversal/recovery. By moving and arranging the branching member 15 for switching the paper feed path, the paper P is guided to the reversal/refeed path after the first surface fixing and to the discharge path after the second surface fixing.

Specifically, when the first side of the sheet P is passed in the double-sided sheet passing mode, the guide member 205 and the branch member 15 are moved to the positions shown in FIG. The sheet P is guided to the reversing/refeeding path without contact. At this time, the position of the guide member 205 becomes the second position.

When the second side of the sheet P is passed in the double-sided sheet passing mode, the guide member 205 and the branching member 15 are moved to the positions shown in FIG. Guide P to the discharge route. At this time, the position of the guide member 205 becomes the second position.

The positions of the guide member 205 and the branching member 15 may be moved depending on the paper type other than the above-described single-sided printing/double-sided printing and paper thickness. For example, the guide member 205 is set to the first position for recycled paper that easily curls, and the guide member 205 is set to the second position for glossy paper.

Further, the positions of the guide member 205 and the branch member 15 may be moved according to the type of the paper discharge roller. For example, when the paper discharge roller 1301 capable of forming corrugation is used, the guide member 205 is not decurled and the guide member 205 is set to the second position. When the paper discharge roller 1800 not forming corrugation is used, the guide member 205 is used. The guide member 205 is set to the first position in order to perform decurling by.

Various information used for the determination of the sheet passing mode, single-sided printing/double-sided printing, paper thickness, paper type, etc. are set using the information set in the operation display unit 152 provided in the main body shown in FIG. The operation display unit 152 constitutes the setting means in the present invention.

The configuration of the guide member 205 and the driving means of the guide member 205 will be described with reference to FIGS.

FIG. 23 is a view of the pressure side separation/transport member 202 as viewed from the direction of the sheet transport surface. The drive rollers 204 of the pair of conveyance auxiliary rollers 230 are rotatably supported at both ends of the pressure side separation conveyance member 202 via sliding bearings 208. The driving roller 204 is configured to be rotatable by transmitting a driving force from a driving input source to a driving gear 210 that is provided on the shaft of the driving roller 204 via an idler gear 211 and that drives the driving roller 204.

The guide member 205 is disposed downstream of the drive roller 204, and is fixed to the pressure-side separation/conveyance member 202 via sliding bearings 208 at both ends of the drive roller, so that the guide member 205 is coaxially supported by the drive roller 204 and is provided in the drive roller 204. It is configured to be rotatable around the axis. The driving roller 204 rotates in contact with the inner diameter portion of the sliding bearing 208, and the guide member 205 contacts the outer diameter portion of the sliding bearing 208 and rotates.

With the above-described configuration, the distance gap between the drive roller 204 and the guide member 205 can be configured to have the smallest dimension tolerance stacking of components (only the radial distance tolerance from the axial center of each component). The guide member 205 can be moved while the distance between the guide member 205 and the guide member 205 is maintained with high accuracy.

As shown in FIG. 22, since the guide member 205 and the branching member 15 located downstream are movable independently of each other depending on the paper passing mode, the guide member 205 and the branching member 15 when viewed from the viewpoint direction of FIG. It is necessary to prevent each of them from interfering with each other even if they overlap with each other.

Therefore, the guide member 205 is formed in a rib shape having a plurality of claws over the length. As shown in FIG. 29, the ribs on the claws of the branch member 15 are inserted between the claw-shaped ribs of the guide member 205, so that they can overlap and be independently movable.

Further, as shown in FIG. 24, the drive roller 204 is a roller having a plurality of rubber rollers arranged therein, and is configured so that the rib shape of the guide member 205 is inserted into a portion where there is no rubber roller. .. Therefore, the outer diameter of the rubber roller and the rib of the guide member 205 overlap each other when viewed from the direction of the cross section Y shown in FIG.

The leading end of the guide member 205 is arranged in proximity to the nip portion of the pair of conveyance assisting rollers 230 (circle mark in FIG. 24). This configuration is because it is important to dispose the leading end of the guide member close to the drive roller 204 in order to surely guide the sheet P discharged from the pair of conveyance assisting rollers 230. Further, from the viewpoint of curl correction effect of bending the sheet P coming out of the conveyance auxiliary roller pair 230 and stabilization of conveyance property, it is important to dispose the leading end close to the nip portion.

FIG. 26 shows a comparative diagram when the tip end of the guide member is placed so as to overlap the drive roller and when the tip end of the guide member is placed at a gap from the rubber outer diameter of the drive roller. A solid line L in the figure shows a case where the tip end of the guide member 205 is arranged so as to overlap the drive roller 204, and a broken line L′ is arranged so that the tip end of the guide member 205 is separated from the rubber outer diameter of the drive roller 204. It shows the case where it is made.

When the tip end of the guide member 205 is arranged away from the rubber outer diameter of the drive roller 204, in order to make the curl correction effect by the guide member 205 the same, the guide member 205 is arranged as indicated by the broken line L′. In this case, the paper ejected from the conveyance auxiliary roller pair 230 is ejected in the direction perpendicular to the line connecting the centers of the rollers of the conveyance auxiliary roller pair 230, and therefore the contact angle θ′ between the leading edge of the paper and the guide member 205. Is smaller than the contact angle θ in the overlapping arrangement.

When this contact angle becomes smaller, the leading edge of the sheet buckles and is bent and conveyed, and in the worst case, the risk of jamming increases. On the contrary, when the guide member 205 is arranged such that the contact angle between the leading end of the sheet and the guide member 205 is large (shallow), the curl correction effect of bending the sheet P by the guide member 205 is reduced.

From the above point of view, it is necessary to bring the tip of the guide member 205 closer to the nip of the conveyance assisting roller pair 230. Therefore, the ribs of the guide member 205 are inserted in the portion where there is no rubber roller, using the conveyance assisting drive roller 204 as a roller. Is configured as follows.

As shown in FIG. 24A, the guide member 205 is biased by a tension spring 209 in the direction of closing the conveyance path, and the stopper portion 205A of the guide member 205 contacts a part of the pressure side separation conveyance member 202. It is configured to be stopped at a position. The position of the guide member 205 at this time is the first position that changes the angle of the sheet P discharged from the pair of transport auxiliary rollers 230 in the transport direction shown in FIG.

As shown in FIG. 25A, on the main body side of the image forming apparatus 1, a solenoid 220, which is a driving unit for moving the guide member 205 to a second position that does not change the angle of the sheet P conveyance direction, and a link member. 221 and 221 are provided. The link member 221 constitutes the link mechanism according to the present invention.

As shown in FIGS. 27 and 28, the link member 221 is connected to the guide member 205 and is rotatable around a fulcrum 221A, and when the solenoid 220 is attracted, the tip of the link member 221 is lifted. As a result, the guide member 205 comes into contact. When the solenoid 220 is turned on, the suction force is generated, and when it is turned off, the suction force is not generated.

By making the attraction force of the solenoid 220 larger than the biasing force of the tension spring 209 to the guide member 205, the guide member 205 rotates counterclockwise and moves to the second position. The position of the guide member 205 when the solenoid 220 is attracted and stopped is the second position shown in FIG. The guide surface of the guide member 205 at the second position is substantially vertical with respect to the horizontal direction, and does not change the transport direction of the paper P.

In the present embodiment, the first position where the positional relationship between the guide member 205 and the conveyance assisting roller pair 230 is severe is configured so that the position is completed within the unit, and the second position is configured in the image forming apparatus 1. Although it is configured to be determined by the solenoid 220 that is the drive means on the main body side and the link member 221, it may be reversed.

Further, a stepping motor or the like may be used as the driving means of the guide member 205 so that the position of the guide member is determined in multiple stages. For example, when it is desired to remove a weak curl, the position of the guide member may be an intermediate position between the first position and the second position.

As described above, the image forming apparatus 1 according to the present embodiment has the operation display unit 152 for setting the type of the paper P fed to the fixing device 20, and the image of the paper P on the downstream side of the fixing device 20 is displayed. The conveyance assist roller pair 230 and the paper P ejected from the conveyance assistance roller pair 230 immediately after the conveyance assistance roller pair 230 are guided to the upstream side of the branching member 15 that switches the discharge route to the outside of the forming apparatus 1 and the double-sided reversal route. And a guide member 205 that operates.

In addition, the first position where the guide member 205 contacts the sheet P and changes the angle formed by the path of the sheet P discharged from the conveyance auxiliary roller pair 230 and the second position where the angle formed by the path of the sheet P does not change. The solenoid 220 and the link member 221 are movable to the position. The solenoid 220 and the link member 221 move the guide member 205 between the first position and the second position according to the type of the paper P set on the operation display unit 152. Is configured to move to any of the positions.

With this configuration, the position of the guide member 205 is moved to the first position or the second position by the solenoid 220 and the link member 221 according to the type of the paper P, so that on/off of the decal can be appropriately set. .. Further, by appropriately setting the decal on/off, it is possible to prevent a conveyance problem due to the decal.

Further, the solenoid 220 and the link member 221 may be configured to move the guide member 205 to either the first position or the second position according to the type of the paper discharge roller. With this configuration, the guide member is moved to the second position when using the paper discharge roller 1301 that gives the waist, and the guide member moves to the first position when using the paper discharge roller 1800 that does not give the waist. By doing so, the degree of decal on the paper P can be made appropriate.

Further, the solenoid 220 and the link member 221 may be configured so that the guide member 205 can be moved to any position between the first position and the second position. With this configuration, the decal by the guide member 205 can be set to an arbitrary degree.

Further, the guide member 205 may be rotatably supported at a position coaxial with the axis of the drive roller 204 of the conveyance auxiliary roller pair 230, and can be moved to the first position and the second position by rotationally moving. With this configuration, the distance gap between the drive roller 204 and the guide member 205 can be configured such that the component dimension tolerance stacking is minimized, and the distance between the drive roller 204 and the guide member 205 can be maintained with high accuracy. The guide member 205 can move in the slumped state.

Further, the solenoid 220 and the link member 221 may change the position of the guide member 205 depending on the thickness of the paper P. With this configuration, the occurrence of contact marks due to contact with the guide member 205 on the thick paper having strong elasticity can be prevented, and the guide member 205 can be set to the second position so that the paper P and the guide member 205 do not come into contact with each other. Further, for the paper P having a paper thickness equal to or smaller than a predetermined value, the guide member 205 can be set to the first position to add stiffness to the paper P.

Further, the solenoid 220 and the link member 221 may be configured so that the guide member 205 can be moved by operating the link member 221 by turning the solenoid 220 on or off.

Further, the conveyance assisting roller pair 230 is composed of a driving roller 204 made of a rubber roller and a driven roller 203 having a high peeling property on the surface thereof, so that the non-image side of the sheet P becomes the driving roller 204 at the time of single-sided sheet passing. You may comprise. With this configuration, it is possible to prevent toner from adhering and accumulating on the surface of the driven roller 203 that contacts the image surface side.

In the second embodiment, the configuration of the image forming apparatus in which the decurling unit is turned on/off according to the paper thickness is shown. On the other hand, factors affecting the occurrence of curl include not only the paper thickness but also the moisture content in the paper at the time of fixing. For example, it is known that the curl after fixing is more likely to occur as the moisture content in the paper is higher, and the curl after fixing is less likely to occur as the moisture content is lower, for reasons such as high humidity.

An image forming apparatus according to a third embodiment described below aims to prevent a conveyance problem due to a decal by appropriately setting on/off of a decurling unit according to humidity.

(Third Embodiment)
The image forming apparatus according to the third embodiment will be described below.

In the image forming apparatus according to the third embodiment, the same components as those in the first and second embodiments are the same as those in the first and second embodiments shown in FIGS. 1 to 29. Description will be given using the same reference numerals, and only the differences will be described in detail.

The image forming apparatus 1 includes an image forming unit A, a fixing device 20, an operation display unit 152, a guide member 205, a solenoid 220, a temperature/humidity sensor 1600, a temperature/humidity sensor 1700, and a control unit 100 (see FIG. 32). ) And is configured to include.

As shown in FIG. 30, the temperature/humidity sensor 1600 is provided near the operation unit 150 above the image forming apparatus 1 (see FIG. 2 ). The temperature/humidity sensor 1600 detects the temperature and humidity of the outside air of the image forming apparatus 1. The temperature/humidity sensor 1600 constitutes the humidity detecting means according to the present invention.

In the example shown in FIG. 30, the temperature/humidity sensor is provided above the image forming apparatus 1, but as shown in FIG. 31, the temperature/humidity sensor 1700 is provided inside the paper feed tray 10 provided below the image forming apparatus 1. Good. The temperature/humidity sensor 1700 detects temperature and humidity in the image forming apparatus 1 or the paper feed tray 10.

The means for detecting the outside air of the image forming apparatus 1 and the temperature and humidity inside the apparatus (or inside the paper feed tray 10) are not necessarily limited to these.

Next, the configuration of the control unit 100 will be described with reference to FIG.

As shown in FIG. 32, a temperature/humidity sensor 1600, a temperature/humidity sensor 1700, an operation display unit 152, and a solenoid 220 are connected to the control unit 100.

The control unit 100 includes a microcomputer including, for example, a CPU, a RAM, a ROM, an input/output interface, and the like, and moves the guide member 205 according to the type of the paper P and the outside air or the humidity in the image forming apparatus 1. To control.

The temperature/humidity sensor 1600 detects the humidity of the outside air, and the temperature/humidity sensor 1700 detects the humidity inside the image forming apparatus 1. The operation display unit 152 can set various types of information such as the type of the sheet P, the sheet thickness, single-sided printing/double-sided printing, and displays such information. The solenoid 220 interlocks with the link member 221 to move the guide member 205 to either the first position or the second position.

FIG. 33 is a diagram comparing the relationship between the on/off state of the decurler depending on the paper thickness and humidity in the other image forming apparatus in the present situation and the image forming apparatus 1 of the present embodiment. In FIG. 33, ON is a state in which the guide member 205 is moved to the first position shown in FIG. 22(a) to turn on the decurler, and OFF is a second position shown in FIG. 22(b). It shows the state of moving and turning off the decurler.

Other current image forming apparatuses are configured to control on/off of the decurler according to the paper type and the paper thickness of the paper P. When the paper P is thin paper or plain paper, the decurler is turned on and the guide member 205 is moved to the first position. When the paper P is thick paper, the decurler is turned off and the guide member 205 is moved to the second position. Here, thin paper means a paper thickness of 59 g/m 2 or less, plain paper means a paper thickness of more than 59 g/m 2 and 160 g/m 2 or less, and thick paper means a paper thickness of more than 160 g/m 2. ..

On the other hand, the image forming apparatus 1 according to the present embodiment controls on/off of the decurler not only by the type and thickness of the sheet P but also by the humidity. The humidity here is the temperature of the outside air of the image forming apparatus 1 detected by the temperature/humidity sensor 1600, or the humidity in the image forming apparatus 1 or the paper feed tray 10 detected by the temperature/humidity sensor 1700.

When the paper type of the paper P is thin paper, the decurler is turned on and the guide member 205 is moved to the first position regardless of whether the humidity is high or low. When the paper type of the paper P is plain paper and the humidity is low, curling is unlikely to occur, so the decurler is turned off and the guide member 205 is moved to the second position. When the paper type of the paper P is plain paper and the humidity is high, curling is likely to occur, so the decurler is turned on and the guide member 205 is moved to the first position. When the paper type of the paper P is thick paper, the decurler is turned off and the guide member 205 is moved to the second position regardless of whether the humidity is high or low.

It should be noted that the case where the humidity is high here refers to the case where the humidity exceeds 50%, and the case where the humidity is low refers to the case where the humidity is 50% or less.

By controlling the on/off of the decurler in consideration of not only the paper thickness but also the humidity in this way, decurling is applied to the paper when curling does not occur in the paper at low humidity or when the curl amount is small. You can prevent it.

FIG. 34 is a flow chart of on/off control of the decurler in the present embodiment.

The control unit 100 determines whether the paper P is a thin paper (step S1). When the paper P is thin paper, the control unit 100 turns on the decurler (step S2), and moves the guide member 205 to the first position by the solenoid 220 and the link member 221 which are the driving means. Next, the control unit 100 ends the determination of whether the decurler is on or off (step S6).

When the paper P is not thin paper, the control unit 100 determines whether the paper P is plain paper (step S3). When the paper P is plain paper, the control unit 100 determines whether the outside air or the humidity inside the image forming apparatus 1 is high humidity (step S4). The controller 100 turns on the decurler when the outside air or the humidity inside the image forming apparatus 1 is high (step S2), and moves the guide member 205 to the first position by the solenoid 220 and the link member 221 which are driving means. To move. Next, the control unit 100 ends the determination of whether the decurler is on or off (step S6).

When the paper P is not plain paper (=thick paper), the controller 100 turns off the decurler (step S5), and moves the guide member 205 to the second position by the solenoid 220 and the link member 221 which are the driving means. To move. Also, when the control unit 100 determines in step S4 that the outside air or the humidity inside the image forming apparatus 1 is low humidity, the decurler is turned off (step S5), and the solenoid 220 and the link member 221 which are the driving means make the first The guide member 205 is moved to the position 2. Next, the control unit 100 ends the determination of whether the decurler is on or off (step S6).

As described above, the image forming apparatus 1 according to the present embodiment has the operation display unit 152 for setting the type of the paper P fed to the fixing device 20, and the image of the paper P on the downstream side of the fixing device 20 is displayed. The conveyance assist roller pair 230 and the paper P ejected from the conveyance assistance roller pair 230 immediately after the conveyance assistance roller pair 230 are guided to the upstream side of the branching member 15 that switches the discharge route to the outside of the forming apparatus 1 and the double-sided reversal route. And a guide member 205 that operates.

Further, the first position where the guide member 205 contacts the sheet P and changes the angle formed by the path of the sheet P discharged from the conveyance auxiliary roller pair 230, and the second position where the angle formed by the path of the sheet P does not change. Has a solenoid 220 and a link member 221 which can be moved to the first position. The solenoid 220 and the link member 221 move the guide member 205 to the first position and the second position according to the type of the paper P set on the operation display unit 152. It is configured to move to any of the positions.

Further, a temperature/humidity sensor 1600 for detecting the humidity of the outside air is further provided, and the solenoid 220 and the link member 221 move the guide member 205 between the first position and the second position according to the humidity detected by the temperature/humidity sensor 1600. It is configured to move to either.

With this configuration, the decal is turned on/off by moving the position of the guide member 205 to the first position or the second position by the solenoid 220 and the link member 221 according to not only the type of the paper P but also the humidity of the outside air. Can be set appropriately. In addition, it is possible to prevent a conveyance problem due to decurling of the paper P which does not curl or has a small curl amount.

Further, a temperature/humidity sensor 1700 for detecting the humidity in the image forming apparatus may be provided.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

According to the present invention, it is possible to prevent a defective conveyance of a sheet by changing the loosening condition according to the conveyance path of the sheet after the sheet discharge section and realize the space saving of the device, and The workability of attaching and detaching the roller holder can be improved, and it is useful for all image forming apparatuses.

1 Image Forming Device 13 Paper Ejection Roller Pair (1 Ejection Roller)
14 Paper Output Tray 15 Branching Member 20 Fixing Device 152 Operation Display Unit (Setting Unit)
205 guide member 220 solenoid (driving means)
221 Link member (driving means)
230 Conveyance Auxiliary Roller Pair 1300 Paper Ejection Section 1301 Paper Ejection Roller (Driven Ejection Roller)
1302 Roller holder 1401 Paper ejection roller (ejection roller)
1501 roller 1502 roller 1503 through shaft 1600 temperature/humidity sensor (humidity detection means)
1700 Temperature and humidity sensor (humidity detection means)
1701 Relay unit 1800 Paper ejection roller (ejection roller)
1801 Roller 1802 Through shaft 1900 Post-processing device A Image forming unit P Paper

Japanese Patent No. 4872471 JP 2001-48392 A JP-A-6-202506

Claims (9)

Image formation having a fixing device that transfers the image formed by the image forming unit onto a sheet and then fixes the image on the sheet, and a setting unit that sets the type of the sheet fed to the fixing device. In the device,
On the downstream side of the fixing device and on the upstream side of the branching member that switches the path for discharging the paper to the outside of the image forming apparatus and the double-sided reversal path, the conveyance auxiliary roller pair and the conveyance auxiliary roller immediately after the conveyance auxiliary roller pair. A guide member for guiding the sheet discharged from the pair,
A first position in which the guide member comes into contact with the sheet and changes an angle formed by the guide member and the sheet discharged from the conveyance auxiliary roller pair; and the sheet discharged from the conveyance auxiliary roller pair. A driving unit movable to a second position that does not change an angle formed by the guide member,
An image forming apparatus, wherein the guide member is arranged at the second position regardless of the type of the sheet when performing double-sided printing on the sheet. The image forming apparatus according to claim 1, wherein the driving unit is capable of moving the guide member to an arbitrary position between the first position and the second position. The guide member is rotatably supported at a position coaxial with the drive-side roller shaft of the conveyance auxiliary roller pair, and is configured to be movable to the first position and the second position by rotationally moving. The image forming apparatus according to any one of claims 1 and 2, which is characterized. The image forming apparatus according to claim 1, wherein the driving unit changes a position of the guide member according to a paper thickness of the paper. The drive unit includes a solenoid provided in the main body of the image forming apparatus and a link mechanism that is interlocked with the solenoid and is connected to the guide member, and turns the solenoid on or off, thereby The image forming apparatus according to any one of claims 1 to 4, wherein the guide member is movable by operating a link mechanism. The pair of conveyance assisting rollers are composed of a driving roller made of a rubber roller and a driven roller having a surface having a peeling property, and the non-image side of the sheet at the time of single-sided sheet passing is the driving roller. The image forming apparatus according to any one of claims 1 to 5. Further comprising a humidity detecting means for detecting the humidity of the outside air,
7. The driving unit moves the guide member to either the first position or the second position according to the humidity detected by the humidity detecting unit. The image forming apparatus according to claim 1. Further comprising a humidity detecting means for detecting the humidity in the image forming apparatus,
7. The driving unit moves the guide member to either the first position or the second position according to the humidity detected by the humidity detecting unit. The image forming apparatus according to claim 1. The image forming apparatus further includes a humidity detecting unit that detects the humidity in the paper feed tray that stores the paper as the humidity in the image forming apparatus.
9. The image according to claim 8, wherein the driving unit moves the guide member to either the first position or the second position according to the humidity detected by the humidity detecting unit. Forming equipment.

Images