JP4201996B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and more particularly to an image forming apparatus having a double-sided printing function.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an image forming apparatus having a double-sided printing function, a double-sided conveyance unit is rotatably supported at a lower fulcrum with respect to the image forming apparatus body, and a conveyance path is also rotatably supported in the double-sided conveyance unit. In general, an image forming apparatus of the above type is used. This improves the operability when a paper jam occurs, and is designed to handle paper jams in the vicinity of the photoconductor and paper jams in the duplex conveyance unit.
[0003]
However, if the guide means is divided into the inside and the outside in order to open the guide means in the duplex conveying unit, it becomes difficult to adjust the distance between the inside guide means and the outside guide means. There was a problem.
In particular, in order to increase the operability of the paper jam processing by opening the nip portion, when the inner guide means has the driven roller of the conveying roller, the pressure of the driven roller acts on the inner guide means, and the guide means Will bend. As a result, the distance between the transport paths is increased, and the pressure applied to the driven roller is not applied, and paper jams due to slippage of the transport rollers, or transfer paper being caught due to the distance between the transport paths being too large may occur.
[0004]
Usually, the cover of the double-sided conveyance unit provided with the outer side guide means is provided with a connection means with the main body of the image forming apparatus, and in order to determine the position of the double-sided conveyance unit, the inner side guide means to the outer side guide. Often, biasing means for biasing in the direction of the means is provided. With this urging means, the duplex conveying unit is automatically opened from the image forming apparatus main body when the connecting means is opened.
However, conventionally, there has been a problem that the conveyance path in the double-sided conveyance unit becomes narrow due to the force of the urging means. In this case, the transfer paper is sandwiched between the guide means, the resistance increases, and a paper jam occurs.
[0005]
There is also a technique in which the guide means after fixing is integrated with the guide means inside the double-sided transport unit in order to improve the removal property of the paper jam in the transport path to the reverse path after fixing. However, in this case as well, it is difficult to ensure an appropriate distance between the guide unit after fixing on the duplex conveyance unit side and the guide unit on the image forming apparatus main body side facing the fixing unit.
[0006]
[Problems to be solved by the invention]
As described above, in an image forming apparatus having a double-sided printing function, it is difficult to improve both the operability of the paper jam processing and the transfer paper conveyance performance.
In view of the above problems, an object of the present invention is to provide an image forming apparatus that achieves both operability of paper jam handling and improved conveyance performance.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the present invention comprises a fixing means for fixing an image formed on a transfer paper,
In an image forming apparatus having a double-sided conveyance unit attached to a side surface of an image forming apparatus main body and rotatably supported by a lower fulcrum,
The duplex conveying unit is
A guide means that is reversely turned upside down on one side of the transfer paper that has passed through the fixing means and guided again toward the fixing means, and is supported rotatably with respect to the duplex unit ;
An outer guide plate that is provided so as to face the guide means, rotates with the duplex conveying unit, and guides the other surface of the transfer paper ;
A transport driven roller attached to a position facing the outer guide plate in the guide means ;
A post-fixing guide unit that is provided in the guide unit and guides a surface of the transfer paper that has passed through the fixing unit on the double-sided conveyance unit side ;
A restricting means for restricting so as to maintain an interval of a double-sided conveyance path formed by the guide means and the outer guide plate;
An urging unit that is attached between the guide unit and the post-fixing guide unit and urges the post-fixing guide unit toward the apparatus main body when the double-sided conveyance unit is set on the image forming apparatus main body ;
And connecting means for connecting the said definitive in the duplex conveying unit provided in the outer guide plate side, the duplex conveying unit and the image forming apparatus main body when the duplex conveying unit is set to the image forming apparatus main body,
A pressure unit provided in the guide unit and pressing a transfer roller attached to the guide unit against the image carrier on the image forming apparatus main body when the double-sided conveyance unit is set on the image forming apparatus main body; br />
The image forming apparatus body
A mating member that locks by being hooked with the connecting means when the duplex conveying unit is set in the image forming apparatus main body ;
The post-fixing guide means opposite the have <br/> the opposing guide plates for guiding the transfer sheet that has passed through the fixing means,
A sum of moments of force pressing the guide means toward the outer guide plate by the pressing means and the biasing means is set to be stronger than a sum of moments of reaction force by the transport driven roller; and A post-fixing guide unit is provided with a position regulating member that regulates the position of the opposing guide plate facing the post-fixing guide unit when the duplex conveying unit is set in the image forming apparatus main body. It shall be the image forming apparatus according to claim. The present invention, in the image forming apparatus, image forming, characterized in that a guide means for preventing the transfer sheet enters between the guide means of the two-sided conveyance unit and the post-fixing guide means A device. The present invention, in the image forming apparatus, the post-fixing guide means are formed by high heat resistant member, and an image forming apparatus, wherein the volume is less than the guide means of the two-sided conveyance unit.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a transfer paper conveyance path in the image forming apparatus of the present invention.
The double-sided conveyance unit is attached to the side surface of the image forming apparatus main body and is rotatably supported at the lower fulcrum.
The double-sided conveyance unit has a double-sided conveyance path for guiding the transfer sheet 15 to the image forming unit again to print the back side after printing one side, and a lower fulcrum with respect to the double-sided conveyance unit so that the double-sided conveyance path can be opened. A guide plate 30 as pivotally supported guide means, conveyance driven rollers 27b, 28b, 29b attached to the guide plate 30, and conveyance rollers 27a, 28a, which are paired with the conveyance driven rollers, respectively. 29a, stoppers 44 and 45 as regulating means for regulating the distance between the double-sided conveyance paths, a post-fixing guide plate 46 attached with a slight backlash to the guide plate 30, and the guide plate 30 and the post-fixing guide plate 46, a spring 47 as an urging unit attached to the main body 46, and a lock lever 21 as a connecting unit with the image forming apparatus main body. .
The main body of the image forming apparatus includes a stay 22 as a counterpart member of the lock lever 21, a transfer roller 13 as a transfer unit, a counter guide plate 48 as a guide unit facing the guide plate 46 after fixing, and a duplex conveyance unit. A pressure spring 50 is provided as pressure means for pressing the guide plate 30 against the double-sided conveyance unit main body when it is set in the forming apparatus.
[0009]
The transfer paper 15 on the paper feed tray 14 is fed to the registration rollers 3a and 3b one by one by the paper feed roller 1 and the friction pad 2, and transferred in synchronization with the image on the photoconductor 9 by the registration rollers 3a and 3b. It is sent to the roller 13. The transfer roller 13 transfers the image and sends it to the upper fixing roller 6 to fix the image by heat and pressure.
When the sheet is discharged as it is, the branch claw 33 does not operate, and the transfer paper 15 passes under the branch claw 33 and is sent to the sheet discharge rollers 8 a and 8 b and is discharged onto the sheet discharge tray 25.
In the case of duplex printing, the branch claw 33 is actuated by a DC solenoid (not shown), and the transfer paper 15 is sent to the reverse roller 31. When the rear end of the transfer paper 15 is detected by the reverse sensor 42, the reverse roller 31 starts reverse rotation, and the transfer paper 15 is switched back and sent to the duplex conveying unit. In the duplex conveyance unit, conveyance drive rollers 27a, 28a, 29a are rotated by a stepping motor (not shown), and the transfer paper 15 is moved downward by conveyance drive rollers 27a, 28a, 29a and conveyance driven rollers 27b, 28b, 29b. To the registration rollers 3a and 3b again. Thereafter, the paper is discharged onto the paper discharge tray 25 by the same operation as described above.
[0010]
FIG. 2 is a detailed view of the duplex conveying unit.
The double-sided conveyance unit can be opened clockwise with respect to the image forming apparatus main body around the lower fulcrum 23. When the image forming apparatus main body is set, the lock lever 21 on the duplex conveyance unit side is hooked on the stay 22 on the image forming apparatus main body side and locked.
The double-sided conveyance unit is based on a double-sided conveyance unit cover 26 made of resin and a stay 36, and includes manual guide plates 37 and 38, a manual sheet feeding roller 18, a manual table 17, and conveyance drive rollers 27a and 28a. 29a, an outer guide plate 32b, and a guide plate 30 are attached.
The guide plate 30 is supported so as to be rotatable in the direction of the arrow with respect to the double-sided conveyance unit cover 26 around a fulcrum 52, and conveyance driven rollers 27b, 28b, and 29b are attached together with bearings (not shown). The transport driven rollers 27b, 28b, and 29b are pressurized in the direction of the transport driving rollers 27a, 28a, and 29a by the leaf spring 53.
Further, the guide plate 30 is integrally formed with stoppers 44 and 45 for restricting the minimum value of the transport gap, so that the transport path is not narrower than a certain interval.
A transfer roller 13 is attached to the guide plate 30, and the transfer roller 13 is pressed against the photoconductor 9 by a pressure spring 50.
[0011]
A post-fixing guide plate 46 is attached to the boss above the guide plate 30 with a slight backlash, and is biased to the left by a spring 47.
Further, the opposing guide plate 48 is provided on the main body side, but a boss with a hole is attached to the opposing guide plate 48, and a position as a regulating means provided on the post-fixing guide plate 46 on both sides. The position is determined by fitting with the regulating member 49.
The position restricting member 49 is a cylindrical boss, and is formed with an abutting rib. The position restricting member 49 restricts the post-fixing guide plate 46 from moving to the left of the position shown in the figure.
[0012]
In the configuration of the present invention described above, the sum of the moments of the force that presses the guide plate 30 against the double-sided conveyance unit by the pressure spring 50 and the spring 47 as the pressure means of the transfer roller 13 is the conveyance driven roller 27b, By setting so as to be stronger than the sum of the moments of reaction force by 28b and 29b, in a state where the double-sided conveyance unit is set in the image forming apparatus main body, the stoppers 44 and 45 for regulating the conveyance gap of the guide plate 30 are provided. The double-sided conveyance unit cover 26 and the outer guide plate 32b are in contact with each other, and the lock lever 21 is regulated by the left side of the stay 22 to determine the position of the double-sided conveyance unit. It is regulated in the direction of the guide plate 48. Thereby, both the conveyance gap of the conveyance path after fixing and the conveyance gap of the double-sided conveyance path are optimized.
[0013]
Further, when the post-fixing guide plate 46 is provided separately from the guide plate 30 of the double-sided conveyance unit as in the present invention, the transfer paper with the leading end greatly curled downward enters the gap between the guide plates. It is possible that a paper jam will occur. As a countermeasure, it is effective to provide steps on both guide plates. However, as a further improvement measure, in the present invention, the transfer paper enters between the guide means 46 after fixing and the guide means 30 of the duplex conveying unit. Guide means 51 for preventing this is provided.
The guide means 51 is preferably an elastic film made of a thin plate such as PET.
Further, the guide means 51 is configured to adhere to the guide plate 46 after fixing.
[0014]
In the present invention, the post-fixing guide plate 46 and the guide plate 30 of the double-sided conveyance unit are provided separately, but the post-fixing guide plate 46 is generally at a considerably high temperature by the fixing roller 6. Resins such as ABS and PS are thermally deformed, and heat-resistant grades such as PC, PET, and PBT are required. However, the heat-resistant grade is more expensive than ordinary materials.
Therefore, in the present invention, the post-fixing guide plate 46 is made as small as possible, and instead the guide plate 30 of the duplex conveying unit is made larger by that amount. The guide plate 30 is made of a normal ABS resin.
[0015]
【The invention's effect】
As described above, according to the present invention, the sum of the moments of the force that presses the guide unit against the duplex conveying unit by the pressurizing unit and the urging unit is set to be stronger than the sum of the moments of the reaction force by the conveyance driven roller. In addition, by providing a position regulating member that regulates the positions of the post-fixing guide plate and the opposing guide plate, the double-sided conveyance path and the post-fixing conveyance path are positioned so that the conveyance gap is constant, and good conveyance performance is achieved. As a result, the conveyance path can be opened, and an image forming apparatus excellent in operability against a paper jam can be provided. Also, a pressure unit provided in the guide unit and presses a transfer roller attached to the guide unit against the image carrier on the image forming apparatus main body side when the duplex conveying unit is set in the image forming apparatus main body. By using a pressure spring for pressing the transfer unit against the photosensitive member, it is possible to provide an image forming apparatus with improved operability and conveyance performance for paper jam processing without increasing costs. Furthermore, according to the present invention, there is provided an image forming apparatus that prevents paper jamming by providing guide means for preventing transfer paper from entering the gap between the guide plate after fixing and the guide plate of the duplex conveying unit. be able to. Further, according to the present invention, the post-fixing guide plate is formed of a resin having high heat resistance, the volume is reduced, and the guide plate of the double-sided conveyance unit is enlarged correspondingly, so that good image formation can be achieved without increasing the cost. An apparatus can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating a transfer paper conveyance path in an image forming apparatus of the present invention.
FIG. 2 is a detailed view of a duplex conveying unit according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Paper feed roller 2 Friction pad 3a, 3b Registration roller 4a, 4b Relay roller 5 Guide plate 6 Fixing roller 7 Pressure roller 8a, 8b Paper discharge roller 9 Photoconductor 10 Developing roller 11 Charging roller 12 Cleaning blade 13 Transfer roller 14 Supply Paper tray 15 Transfer paper 17 Manual feed table 18 Manual feed roller 19 Side fence 21 Lock lever 22 Stay 23 Support shaft 24 Reversing unit 25 Paper discharge tray 26 Double-sided transport unit cover 27a Transport drive roller (entrance)
27b Conveyor driven roller (entrance)
28a Transport drive roller (relay)
28b Conveyor driven roller (relay)
29a Transport drive roller (exit)
29b Conveyor driven roller (exit)
30 Guide plates 31a, 31b Reverse rollers 32a, 32b, 32c Outer guide plate 33 Branch claw 34 Manual friction pad 35 Scanner base 36 Stays 37, 38 Manual guide plate 41 Band 42 Reverse sensor 44 Stopper 45 Stopper 46 Fixing guide plate 47 Spring 48 Opposing guide plate 49 Position regulating member 50 Pressure spring 51 Guide means 52 Support point 53 Plate spring

Claims (3)

Fixing means for fixing the image formed on the transfer paper;
In an image forming apparatus having a double-sided conveyance unit attached to a side surface of an image forming apparatus main body and rotatably supported by a lower fulcrum,
The duplex conveying unit is
A guide means that is reversely turned upside down on one side of the transfer paper that has passed through the fixing means and guided again toward the fixing means, and is supported rotatably with respect to the duplex unit ;
An outer guide plate that is provided so as to face the guide means, rotates with the duplex conveying unit, and guides the other surface of the transfer paper ;
A transport driven roller attached to a position facing the outer guide plate in the guide means ;
A post-fixing guide unit that is provided in the guide unit and guides a surface of the transfer paper that has passed through the fixing unit on the double-sided conveyance unit side ;
A restricting means for restricting so as to maintain an interval of a double-sided conveyance path formed by the guide means and the outer guide plate;
An urging unit that is attached between the guide unit and the post-fixing guide unit and urges the post-fixing guide unit toward the apparatus main body when the double-sided conveyance unit is set on the image forming apparatus main body ;
And connecting means for connecting the said definitive in the duplex conveying unit provided in the outer guide plate side, the duplex conveying unit and the image forming apparatus main body when the duplex conveying unit is set to the image forming apparatus main body,
A pressure unit provided in the guide unit and pressing a transfer roller attached to the guide unit against the image carrier on the image forming apparatus main body when the double-sided conveyance unit is set on the image forming apparatus main body; br />
The image forming apparatus body
A mating member that locks by being hooked with the connecting means when the duplex conveying unit is set in the image forming apparatus main body ;
The post-fixing guide means opposite the have <br/> the opposing guide plates for guiding the transfer sheet that has passed through the fixing means,
A sum of moments of force pressing the guide means toward the outer guide plate by the pressing means and the biasing means is set to be stronger than a sum of moments of reaction force by the transport driven roller; and A post-fixing guide unit is provided with a position regulating member that regulates the position of the opposing guide plate facing the post-fixing guide unit when the duplex conveying unit is set in the image forming apparatus main body. An image forming apparatus. The image forming apparatus according to claim 1.
An image forming apparatus comprising a guide unit for preventing transfer paper from entering between the post-fixing guide unit and the guide unit of the duplex conveying unit . The image forming apparatus according to claim 1, wherein
The image forming apparatus , wherein the post-fixing guide unit is formed of a member having high heat resistance and has a volume smaller than that of the guide unit of the double-sided conveyance unit .

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