The present invention relates to an image forming apparatus.
In an image forming apparatus, such as a copier and a laser beam printer, an electrophotographic system, which forms toner images using an image bearing member, is known. The image forming operation of the electrophotographic type image forming apparatus is generally as follows. First an exposing unit forms an electrostatic latent image on a uniformly charged photosensitive member by performing exposure based on image information. Next a developing unit develops the electrostatic latent image to form a toner image. Next a transfer unit transfer the toner image onto a recording material. Then a fixing unit heats and presses the recording material so as to fix the toner image onto the recording material. The recording material, on which the toner image is transferred, passes through a discharged paper conveying unit which is disposed downstream from the fixing unit, is guided to a discharging unit, and is discharged to a discharge paper tray disposed outside the image forming apparatus main body.
In the above mentioned image forming operation, the temperature of the recording material is risen by heating. If the recording material is transported in the high temperature state, the toner on the recording material may not completely solidify and have viscosity in some cases. If the recording material on which toner is not completely solidified contacts a conveying guide, the toner may adhere to the conveying guide. Further, the recording materials loaded on the discharged paper tray may stick to each other. Furthermore, if the internal temperature of the image forming apparatus is increased by the high temperature recording material and the discharged paper conveying unit reaches a high temperature, components may thermally expand or deform, and as a result, the contact state between the recording material and the components may change, and a conveying failure may occur.
In order to control this temperature rise of the recording material, a method of cooling the recording material of which temperature has risen high was proposed. For example, Japanese Patent Application Publication No. 2012-073335 and Japanese Patent Application Publication No. 2020-112709 disclose a method of cooling the recording material and the discharged paper conveying unit by blowing air into the discharged paper conveying unit from the lower part, and releasing heat out of the apparatus by exhausting the air from the upper part of the discharged paper conveying unit.
In recent years, image forming apparatuses are demanded to have higher productivity and smaller sizes, hence heat generated by the fixing unit tends to increase, and the temperature of recording materials also tends to increase. However, if the recording material is conveyed in the high temperature state, the toner on the recording materials contacts the conveying guide before completely solidifying, which causes such problems as the adhesion of toner on the conveying guide, and the sticking between the recording materials that are loaded on the discharged paper tray. Further, a part of the heat generated by the heating of the recording materials remains in the vicinity of the fixing apparatus, and the heat that accumulated increases each time a toner image on a recording material is fixed. As a result, the internal temperature of the image forming apparatus increases, which may cause thermal expansion and deformation of components constituting the image forming apparatus. This may change the contact state of the components and the recording materials, and may cause a conveying failure. In the case where the spacing of recording materials, which are continuously conveyed, is narrowed by improve productivity as well, the recording materials and the discharged paper conveying unit must be cooled efficiently.
With the foregoing in view, it is an object of the present invention to increase the cooling effect to cool the recording materials and the interior of the image forming apparatus, while avoiding an increase in the size of the apparatus.
The present invention provides an image forming apparatus, comprising:
an image forming unit configured to form a toner image on one surface of a recording material;
a fixing unit that includes a heating unit and is configured to heat and fix the toner image formed on the one surface of the recording material;
a discharging unit configured to discharge the recording material, on which the toner image is fixed by the fixing unit, to a discharged paper tray; and
a guide member that is disposed between the fixing unit and the discharging unit and is configured to form a recording material conveying path for conveying the recording material from the fixing unit to the discharging unit, wherein
on the guide member, a blowing port to send air to the recording material conveying path and a suction port to suck air from the recording material conveying path are disposed on a same surface so as not to cross over the recording material being conveyed.
According to the present invention, the cooling effect to cool the recording materials and the interior of the image forming apparatus can be improved, while avoiding an increase in the size of the apparatus.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Examples to carry out the present invention will be described in detail with reference to the drawings and embodiments. Unless otherwise specified, the functions, materials, dimensions, shapes and relative positions of the components described in the embodiments are not intended to limit the scope of the invention. Further, in the following description, the functions, materials, dimensions, shapes and relative positions of members are the same as the initial description, unless otherwise specified.
Embodiment 1 will be described with reference to
The image forming unit F includes four process cartridges 3 (3a, 3b, 3c and 3d), a laser scanner 4 (optical unit) and a transfer unit 5. Each process cartridge 3 (3a to 3d) is a cartridge in which process units that act on a photosensitive drum 1 (image bearing member) are integrated, and is designed to be detachable from the image forming apparatus P. The four process cartridges 3a to 3d have identical structures, but the colors for forming an image are different. In other words, the four process cartridges 3a to 3d use yellow (Y), magenta (M), cyan (C) and black (Bk) toner respectively. In the following description, for the configuration common to each color, each process cartridge 3a, 3b, 3c or 3d is generally referred to as a process cartridge 3, omitting the suffixes a to d. For the other composing elements as well, suffixes a, b, c and d correspond to Y, M, C and K respectively, but the suffixes may be omitted if a distinction in color is not required.
The process cartridge 3 is constituted of a developing unit D and a cleaner unit C. The developing unit includes a developing roller 21, a developer coating roller 22 and a toner container 23. The cleaner unit C, on the other hand, includes a photosensitive drum 1 (image bearing member), a charging roller (charging unit 2), and a cleaning blade (cleaning unit 27). A series of image forming steps performed by the image forming unit F is controlled by a control unit (not illustrated) which is constituted of an information processing unit, including a processor, memory, and the like. The control unit operates in accordance with input which the user performed via an operation panel, and the instructions of the program developed in the memory, and forms an image by sending and receiving information, such as instruction signals, to/from each composing element of the apparatus.
Both edges of the photosensitive drum 1 are rotatably supported by a flange, and the photosensitive drum 1 is rotary-driven in the clockwise direction (arrow direction) in
The charging unit 2 is a conductive roller, and when this roller is contacted to the surface of the photosensitive drum 1 and a charging bias voltage is applied to the roller from a power supply (not illustrated), the surface of the photosensitive drum 1 is uniformly charged. The laser scanner 4 is disposed below the process cartridge 3 in the perpendicular direction, and emits a light to the photosensitive drum 1 for exposure based on image signals. Thereby an electrostatic latent image is formed on the photosensitive drum 1. For the image signals, the signals that the control unit received from outside the apparatus and stored in the memory can be used.
The toner containers 23a to 23d of the developing unit D store toner of each color: yellow (Y), magenta (M), cyan (C) and black (Bk) respectively. The developing roller 21 of the developing unit D is adjacent to the surface of the photosensitive drum 1, and is rotary-driven by a driving unit (not illustrated), and also develops the electrostatic latent image on the photosensitive drum 1 onto a toner image by applying a developing vias voltage using a developing bias power supply (not illustrated).
An intermediate transfer belt 120, included in an intermediate transfer member unit (transfer unit 5), is stretched around a driving roller and a tension roller, and tensile force is applied to the intermediate transfer belt 120 by a tension roller. Primary transfer rollers 6a to 6d, included in the intermediate transfer member unit, are disposed on the inner side of the intermediate transfer belt 120, so as to face the photosensitive drums 1a to 1d via the intermediate transfer belt 120. Transfer bias is applied to the primary transfer roller 6 by a bias applying unit (not illustrated). Toner images that are formed on the photosensitive drums 1a to 1d are primary-transferred onto the intermediate transfer belt 120 sequentially from the photosensitive drum 1a when positive polarity bias is applied to the primary transfer roller 6. The four colors of the toner images in the superimposed state on the intermediate transfer belt are transported to a secondary transfer unit 15.
A feeding apparatus H is constituted of a paper feeding roller 9, which feeds a recording material S from a paper feeding tray 11 storing recording materials S, and a conveying roller pair 10 which transports the fed recording material S. The user extracts the paper feeding tray 11 from the apparatus main body, sets the recording materials S, and inserts the paper feeding tray 11 back into the main body, thereby the recording materials S can be replenished. The recording materials S stored in the paper feeding tray 11 are pressed by the paper feeding roller 9, and are separated one by one by a separating pad, and conveyed on a conveying path J.
A transfer bias is applied to a secondary transfer roller 16 by a bias applying unit (not illustrated). By applying a positive polarity bias to the secondary transfer roller 16 in the secondary transfer unit 15, the four-color toner image on the intermediate transfer belt 120 is secondarily-transferred to the recording material S conveyed on the conveying path J.
The fixing apparatus 14 (fixing unit) is constituted of a heating unit 14a that heats the recording material S and a pressure roller (nip forming member) 14b that presses the recording material S to the heating unit 14a, such that a nip, to hold and convey the recording material, is formed. The fixing apparatus 14 also includes a fixing conveying roller pair 19 that conveys the recording material S, which passed through the nip, outside the fixing apparatus 14 (toward downstream of the conveying path J). The heating unit 14a heats the recording material S to which pressure was applied in the nip formed between the heating unit 14a and the pressure roller 14b. By the heat and pressure applied in the nip, the toner image transferred onto the recording material S is fixed to the recording material S. One of the two surfaces of the recording material S becomes a recording surface on which the toner image, transferred by the image forming unit F, is fixed by the fixing apparatus 14. In the case of forming images on both surfaces of the recording material S, the recording surface and the opposite surface thereof are reversed after an image is formed on one recording surface as already mentioned, then another image is formed on the opposite surface of the recording surface.
After fixing the image, the recording material S, discharged from the fixing apparatus 14 by the fixing conveying roller pair 19, passes through a section between a lower guide member 17 and an upper guide member 25 which are disposed between the fixing apparatus 14 and discharging roller pair 18 (discharging unit), and is discharged onto a discharged paper tray 31 by the discharging roller pair 18. By the above sequence of steps, image formation on the recording material S completes.
In the case of forming images on both surfaces of the recording material S, the position of a flapper 23 is switched, so that the tip of the flapper 23 comes onto the conveying path J. Thereby the recording material S that passed the fixing apparatus 14 is conveyed to a reversing roller pair 24. Then the direction of the recording material S is reversed by the reversing roller pair 24, and is conveyed again to the secondary transfer unit 15 via a double-sided path (not illustrated). Thereby an image is also formed on opposite side surface of the recording material S.
Configuration to Cool Recording Material S
A configuration to cool the recording material S and the inside of the image forming apparatus P will be described with reference to
The lower guide member 17 includes blowing ports 105 to send air and a suction port 102 to suck air. Since both the blowing ports 105 and the suction port 102 are disposed on a lower guide member 17, the blowing ports 105 and the suction port 102 are disposed on the same plane, without crossing over the recording material S that is conveyed on the conveying path J. Because of this disposition, the blowing ports 105 and the suction port 102 face one surface of the recording material S that is being conveyed. As a result, air can be efficiently sent to the surface where the toner image is transferred. The suction port 102 and a suction fan 101 are disposed on the lower guide member 17 at positions facing an approximate center portion of the recording material S, in a direction orthogonal to the conveying direction of the recording material S. Here the approximate center portion of the recording material S need not be exactly in the center, but preferably is in an area where the cooling effect by suction is implemented evenly on both sides of the recording material S. The blowing ports 105 are disposed on both sides of the suction port 102 in the direction orthogonal to the conveying direction of the recording material S (X direction in
In Embodiment 1, air, which is sent to the blowing ports 105 described in
According to the configuration of Embodiment 1 as described with reference to
As a result, an increase in the temperature of the recording material S, the ambient temperature in the vicinity of the fixing conveying roller pair 19 and the internal temperature of the image forming apparatus P can be controlled. This means that problems caused by an increase in the internal temperature of the image forming apparatus P can be controlled.
In the lower guide member 17, the blowing ports 105 and the suction port 102 are disposed on a same surface without crossing over the recording material S. Therefore the air circulation between the blowing ports 105 and the suction port 102 is not interrupted, even while the recording material S is being conveyed by the fixing conveying roller pair 19 and the discharging roller pair 18. Hence even if a case where the recording materials S are continuously conveyed to improve productivity and the spacing between the recording materials S becomes narrow, the circulation paths of the air are not interrupted.
In Embodiment 1, in order to ensure the gap G, the recording material S does not contact with the lower guide member 17 while the recording material S is being pulled to the discharging roller pair 18 between the fixing conveying roller pair 19 and the discharging roller pair 18.
In Embodiment 1, the air flow, in the case when the recording material S is being conveyed from the fixing apparatus 14 to the discharging roller pair 18, was described, but the recording material S and the interior of the apparatus can be cooled in the same manner, even in a case where the recording material S is conveyed from the fixing apparatus 14 to the reversing roller pair 24, to form images on both sides of the recording material S.
In Embodiment 1, the suction port 102 and the blowing ports 105 are disposed on the lower guide member 17, which is disposed between the fixing apparatus 14 and the discharging roller pair 18. However, the guide member used here is not limited to the lower guide member 17, and a similar effect can be implemented even in a case where the suction port and the blowing port are disposed on the upper guide member 25 to circulate air.
Embodiment 2 of the present invention will be described next with reference to
In the apparatus, the suction fan 101 sucks air in the section between the fixing apparatus 14 and the discharging roller pair 18. Since this section is a region where the recording material S, which was heated in the fixing step, is conveyed, the temperature of the air to be sucked is relatively high, which may increase the temperature of the suction fan 101. In Embodiment 2, however, fresh air sent from the blowing fan 110 can be applied to the suction fan 101, hence a temperature increase in the suction fan 101 can be controlled. As a consequence, the effect of Embodiment 1, that is, an increase in the cooling function in the interior of the image forming apparatus while avoiding an increase in the size of the apparatus, can be further improved.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2021-024574, filed Feb. 18, 2021, which is hereby incorporated by reference wherein in its entirety.
Number | Date | Country | Kind |
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2021-024574 | Feb 2021 | JP | national |
Number | Name | Date | Kind |
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9811030 | Masuda | Nov 2017 | B2 |
11208286 | Morita | Dec 2021 | B2 |
20120201564 | Masuda | Aug 2012 | A1 |
20190332053 | Kawasumi | Oct 2019 | A1 |
Number | Date | Country |
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4886018 | Feb 2012 | JP |
4908944 | Apr 2012 | JP |
2012073335 | Apr 2012 | JP |
5353333 | Nov 2013 | JP |
6083999 | Feb 2017 | JP |
2020112709 | Jul 2020 | JP |
2021051255 | Apr 2021 | JP |
Number | Date | Country | |
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20220260952 A1 | Aug 2022 | US |