Patent Application
20230384733
The present disclosure relates to an image forming apparatus for forming an image on a sheet.
Image forming apparatuses such as copying machines and printers are used in various situations. For example, the users range from a small number of users who print on a small number of sheets to a large number of users who print on a large number of sheets. In the case of printing on a large number of sheets, an image forming apparatus may be operated continuously to perform continuous printing.
To handle the continuous printing, it is necessary to cool down heat generation members including a cartridge, and heated components. Japanese Patent Application Laid-Open No. H05-27612 discusses a configuration for cooling down a transfer roller.
The present disclosure is directed to an image forming apparatus capable of cooling down a transfer roller.
According to an aspect of the present disclosure, an image forming apparatus for forming an image on a sheet includes a rotatable image bearing member configured to bear a toner image, a transfer roller configured to transfer the toner image from the rotatable image bearing member onto the sheet, a fan, and a duct extending in a parallel direction to a shaft direction of the transfer roller, wherein the duct includes an inflow port on a first end side of the duct in the parallel direction and is configured to guide, from the first end side to a second end side of the duct, air that has flowed into the duct through the inflow port, wherein the duct further includes, in an area opposing the transfer roller, a first opening portion that is provided at a position closer to the first end side than to the second end side, and a second opening portion that is provided at a position closer to the second end side than to the first end side, in the parallel direction, and wherein the air supplied to the duct by the fan through the inflow port passes through the first opening portion and the second opening portion, and is supplied to the transfer roller.
Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Exemplary embodiments of the present disclosure will be described in detail below with reference to the attached drawings. Dimensions, materials, shapes of components and relative arrangements thereof described in the exemplary embodiments can be changed appropriately depending on the configuration of an apparatus to which any of the exemplary embodiments is applied and various conditions.
An overall configuration of an image forming apparatus 1 according to a first exemplary embodiment will be schematically described with reference to
In the description of the configuration of the image forming apparatus 1, a left side surface of the main body in
In the main body of the image forming apparatus 1, a pickup roller 81 is provided to feed the sheets S placed in the sheet feed cassette 80 one by one from the sheet feed cassette 80 to the inside of the main body. A conveyance roller 51 and a conveyance opposing roller 52 are also disposed in the main body to receive the sheet S fed by the pickup roller 81 and further convey the sheet S to the downstream side.
A duplex conveyance path 70 is disposed above the sheet feed cassette 80, and a core frame unit 100 is disposed above the duplex conveyance path 70. The core frame unit 100 includes a core frame 101 and fixed to a left frame 2. A process cartridge 10 is disposed above the core frame unit 100. The process cartridge 10 includes a photosensitive drum 11 that is rotatable and serves as an image bearing member for bearing a toner image.
The core frame 101 includes a transfer roller 91 disposed below the process cartridge 10 and opposing the photosensitive drum 11. The transfer roller 91 is configured to rotate while nipping the sheet S in cooperation with the photosensitive drum 11 and transfer the toner image borne on the photosensitive drum 11 onto the sheet S.
A laser scanner unit 30 for forming an electrostatic latent image on the photosensitive drum 11 is disposed above the process cartridge 10. A scanner frame 31 is disposed on an upper surface of the laser scanner unit 30, and the laser scanner unit 30 is fixed to the scanner frame 31. A front door 40 is disposed to the left of the process cartridge 10 in
A fixing unit 20 is disposed downstream of the photosensitive drum 11 and the transfer roller 91 in a conveyance direction of the sheet S. A duplex switching flapper 66, a switchback roller 62, a sheet discharge roller 62a, and a duplex switchback roller 62b are disposed downstream of the fixing unit 20 in the conveyance direction of the sheet S, and a sheet discharge roller pair 61 is disposed thereabove. A central processing unit (CPU) is included in a control unit (not illustrated) of the image forming apparatus 1, and comprehensively controls the image forming operation of the image forming apparatus 1.
Thus, in the present exemplary embodiment, to cool down the photosensitive drum 11, the transfer roller 91 in direct contact with the photosensitive drum 11 or in contact with the photosensitive drum 11 via the sheet S is cooled down. Cooling down the transfer roller 91 enables cooling down the photosensitive drum 11, which prevents the temperature of the photosensitive drum 11 from becoming too high and melting the toner.
Referring to
The sheet S is fed from the sheet feed cassette 80 by the pickup roller 81, and reaches the conveyance roller 51 and the conveyance opposing roller 52. The sheet S (the recording material) is further conveyed by rotation of the conveyance roller 51 and the conveyance opposing roller 52. At this time, a toner image is developed on the photosensitive drum 11 in synchronization with the operation of feeding the sheet S.
The sheet S then enters into a nip portion formed by the photosensitive drum 11 and the transfer roller 91.
At the nip portion formed by the photosensitive drum 11 and the transfer roller 91, the toner image formed on the photosensitive drum 11 is transferred onto the sheet S. The toner image transferred to the sheet S is heated and pressed by the fixing unit 20 including a fixing roller, whereby the toner is melted and fixed on the sheet S.
In the case of one-sided printing, the sheet S with the image fixed thereon reaches the duplex switching flapper 66, is conveyed to a sheet discharge conveyance path 67 by the switchback roller 62 and the sheet discharge roller 62a, and then reaches the sheet discharge roller pair 61. The sheet discharge roller pair 61 then discharges the sheet S to a sheet discharge tray 65 and the image forming operation ends. The rotation of the fan 110 stops when the image forming operation ends.
In the case of two-sided printing, a drive source (not illustrated) changes the state of the duplex switching flapper 66 to guide the sheet S with the image fixed thereon toward the switchback roller 62 and the duplex switchback roller 62b. The sheet S is then conveyed to a switchback conveyance path 64 by the switchback roller 62 and the duplex switchback roller 62b.
The switchback roller 62 and the duplex switchback roller 62b stop before the trailing edge of the sheet S reaches a nip portion formed by the switchback roller 62 and the duplex switchback roller 62b, and then start rotating reversely. The sheet S is then conveyed to the duplex conveyance path 70.
The sheet S passes through the duplex conveyance path 70, is conveyed again to the conveyance roller 51 and the conveyance opposing roller 52, and printing is performed on the second side of the sheet S. Thereafter, the same operation as that in the one-sided printing is performed.
The fan 110 sends air into the duct 101a through an inflow port 111 (see
The inflow port 111 is provided on one end side of the duct 101a in a direction parallel to the shaft direction of the transfer roller 91. The air flowing into the duct 101a through the inflow port 111 is guided by the duct 101a from the one end side toward the other end side. In the present exemplary embodiment, the one end side indicates a position closer to the one end 121 than to the other end 122, and the other end side indicates a position closer to the other end 122 than to the one end 121. The same applies to the transfer roller 91. As illustrated in
As indicated by arrows B, a part of the air flows toward the transfer roller 91 through holes 101b (first openings) serving as a first opening portion provided on one end side of the first guide portion 101g of the duct 101a, and cools down the transfer roller 91. The air then flows in a direction indicated by arrows C.
As indicated by arrows D, a part of the air that has flowed into the duct 101a flows toward the transfer roller 91 through holes 101c (second openings) serving as a second opening portion provided on the other end side of the first guide portion 101g, and cools down the transfer roller 91. The air then joins the air that has entered through the holes 101b and cooled down the transfer roller 91, flows as indicated by an arrow E, and passes out through a discharge portion 101d of the core frame 101.
The discharge portion 101d is a hole for discharging the air guided by the duct 101a to the outside of the image forming apparatus 1, and is provided at the other end side of the transfer roller 91.
The length of the duct 101a in the shaft direction of the transfer roller 91 is longer than the length of the transfer roller 91. The one end 121 of the duct 101a is located at a position farther from the other end 122 of the duct 101a than the one end 131 of the transfer roller 91 in the shaft direction of the transfer roller 91. The other end 122 of the duct 101a is located at a position farther from the one end 121 of the duct 101a than the other end 132 of the transfer roller 91 in the shaft direction of the transfer roller 91. In the present exemplary embodiment, the number of the holes 101b serving as the first opening portion is two and the number of the holes 101c serving as the second opening portion is two.
If a hole through which the air moves from the duct 101a to the transfer roller 91 is provided at only one position on the upstream side of the duct 101a, the temperature of the air that has cooled down the transfer roller 91 on the upstream side becomes high, and the air is unable to cool down the transfer roller 91 enough on the downstream side. To address this issue, by adjusting the positions and areas where the hole is provided, a given portion of the transfer roller 91 can be specifically cooled down. In the present exemplary embodiment, the total area of the two holes 101c serving as the second opening portion is made larger than the total area of the two holes 101b serving as the first opening portion.
This is because the air pressure is high on the one end side of the duct 101a because the distance to the fan 110 is shorter, and the air amount flowing through the holes 101b on the one end side of the duct 101a and the air amount flowing through the holes 101c on the other end side of the duct 101a are different from each other. In the present exemplary embodiment, the configuration in which the core frame 101 includes two sizes of holes, i.e., the holes 101b and the holes 101c is described, but the number of sizes of the openings can be three or more. Further, the air amount can be adjusted by changing the numbers of the holes 101b and the holes 101c, or the distances between the openings of the holes 101b and between the openings of the holes 101c.
It is possible to cool down the transfer roller 91 more efficiently with the configuration in which the total area of the holes 101c serving as the second opening portion is made larger than that of the holes 101b serving as the first opening portion. Alternatively, two or more of the holes 101b or two or more of the holes 101c can be provided. In the configuration according to the present exemplary embodiment, the two holes 101b and the two holes 101c are provided. By providing the first and second openings at different positions in the shaft direction of the transfer roller 91, it is possible to send the air having a low temperature to the transfer roller 91 through each of the first and second openings, and to evenly cool down the transfer roller 91.
Alternatively, three or more holes 101b and three or more holes 101c can be provided. Further alternatively, the holes 101b can be provided at different positions in the shaft direction of the transfer roller 91, and the holes 101c can be provided at different positions in the shaft direction of the transfer roller 91. Further alternatively, the holes 101b can be different in distance therebetween, and the holes 101c can be different in distance therebetween.
In the present exemplary embodiment, the total area of the holes 101c is made larger than that of the holes 101b, but depending on conditions, for example, a condition where the one end side of the transfer roller 91 is close to a heat source and more likely to be high in temperature, the total area of the holes 101c can be made smaller than that of the holes 101b.
The transfer roller 91 cooled down by the air then cools down the photosensitive drum 11 in contact therewith. At the same time, the transfer roller 91 cooled down by the air cools down the sheet S being conveyed. In particular, the sheet S to be subjected to the two-sided printing is higher in temperature than the sheet S in printing on the first side (the front side) because the sheet S has already passed through the fixing unit 20 once. By cooling down the sheet S using the transfer roller 91, it is possible to prevent the heat of the sheet S having a high temperature from transferring to the photosensitive drum 11, and to prevent the temperature rise of the photosensitive drum 11.
As illustrated in
The duct 101a also has multipurpose holes 101j and guide walls 101i. The multipurpose holes 101j do not aim at air discharge, and are provided in the duct 101a for structural reasons. For example, the multipurpose holes 101j are provided to allow a circuit wire bundle to pass therethrough or another member to overlap thereon.
The guide walls 101i are provided to reduce the amount of air to be discharged through the multipurpose holes 101j.
The guide walls 101i are inclined so that the air flowing in the duct 101a flows in a direction away from the multipurpose holes 101j. The amount of air to be discharged through the multipurpose holes 101j is reduced by the guide walls 101i.
The core frame 101 includes a windshield wall 101e. Assuming that a distance between the nearest points of the windshield wall 101e and the transfer roller 91 is L2, the windshield wall 101e is provided by reducing the distance L2 in order to make the air less likely to leak through the gap between the windshield wall 101e and the transfer roller 91.
In this way, the windshield wall 101e prevents the air flowing in the directions indicated by the arrows C and the arrow E in
In the present exemplary embodiment, the fan 110 is disposed closer to the one end side than the inflow port 111, and configured to send air into the main body. Alternatively, any configuration for allowing air to flow into the duct 101a, for example, a configuration in which the fan 110 is disposed closer to the other end side than the discharge portion 101d to suction the air in the main body can be used.
Next, a second exemplary embodiment will be described. The same configurations as those in the first exemplary embodiment are assigned the same reference numerals, and descriptions thereof will be omitted.
The fan 210 continues suctioning the air in the image forming apparatus 1 during the image forming operation, and takes in the air outside the core frame 101 through an inflow port 201d of the core frame 101.
A part of the air that has cooled down the transfer roller 91 flows into the duct 101a through the holes 101c provided in the first guide portion 101g, and flows in a direction indicated by arrows G. Similarly, a part of the air that has flowed into the core frame 101 flows in a direction indicated by arrows H to cool down the transfer roller 91, flows into the duct 101a through the holes 101b provided in the first guide portion 101g, and flows in a direction indicated by arrows I.
The air that has flowed into the duct 101a in the direction indicated by the arrows G joins the air flowing in the direction indicated by the arrows I, flows in a direction indicated by an arrow J, and is discharged from the duct 101a. The transfer roller 91 cooled down in this way cools down the photosensitive drum 11 in contact therewith. The transfer roller 91 also cools down the sheet S being conveyed.
In this way, the windshield wall 101e prevents the air flowing in the directions indicated by the arrow F and the arrows H in
The downstream side of the duct 101a in the direction in which the air in the duct 101a flows, which is the upper side of
Similarly to the first exemplary embodiment, the distances between the openings can also be adjusted.
A third exemplary embodiment will be described. The same configurations as those in the first exemplary embodiment are assigned the same reference numerals, and descriptions thereof will be omitted.
With reference to
Similarly to the first exemplary embodiment, the core frame 301 includes a windshield wall 301e, and the distances of L1 and L2 are similar to those according to the first exemplary embodiment.
As described above, the configuration can be implemented even though the conveyance path has a different shape.
A fourth exemplary embodiment will be described. The same configurations as those in the first exemplary embodiment are assigned the same reference numerals, and descriptions thereof will be omitted.
With reference to
The intermediate transfer unit 440 includes an intermediate transfer belt 441 serving as an image bearing member. Inside the intermediate transfer belt 441, the intermediate transfer unit 440 includes primary transfer rollers 442 (442Y, 442M, 442C, and 442Bk), a tension roller 443, and a secondary transfer opposing roller 444. The intermediate transfer unit 440 further includes a cleaning unit 446 outside the intermediate transfer belt 441. A core frame unit 400 is disposed to the right of the intermediate transfer unit 440 in
The core frame unit 400 includes a core frame 401 and fixed to the left frame 2. The core frame 401 includes a secondary transfer roller 491 opposing the secondary transfer opposing roller 444. An upper stage frame 432 is disposed above the intermediate transfer unit 440. The front door 40 is disposed to the left of the process cartridges 410 in
The fixing unit 20 is disposed above the core frame unit 400. The duplex switching flapper 66 is disposed above the fixing unit 20. A switchback roller pair 362 and the sheet discharge roller pair 61 are disposed to the left of the duplex switching flapper 66 in
Referring to
At this time, toner images are respectively developed by the process cartridges 410 and sequentially transferred onto the intermediate transfer belt 441 in synchronization with the operation of feeding the sheet S. The sheet S is conveyed by the conveyance roller 51 and the conveyance opposing roller 52, and enters into a nip portion formed by the secondary transfer opposing roller 444 and the secondary transfer roller 491.
The toner images developed in an overlapping manner on the intermediate transfer belt 441 (which are also collectively referred to as a developing material image or a color image) are transferred onto the sheet S at timing corresponding to the timing when the sheet S enters into the nip portion. The color image transferred to the sheet S is heated and pressed by the fixing unit 20 including a fixing roller, whereby the toner is melted and fixed on the sheet S. The printing methods in the one-sided printing and the two-sided printing are similar to those according to the first to third exemplary embodiments, and thus descriptions thereof will be omitted.
In the present exemplary embodiment, the secondary transfer roller 491 cooled down by the sent air cools down the intermediate transfer belt 441 in contact therewith. The intermediate transfer belt 441 then cools down the photosensitive drums 411 (411Y, 411M, 411C, and 411Bk) in contact therewith. The secondary transfer roller 491 also cools down the sheet S being conveyed.
Similarly to the core frame 101 in
As described above, any of the first to fourth exemplary embodiments can efficiently send air to a transfer roller and cool down the transfer roller.
While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure 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. 2022-086501, filed May 27, 2022, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-086501 | May 2022 | JP | national |
