Cooling device for recording medium and image forming apparatus

Abstract

To effectively prevent a blocking phenomenon of a recording medium.SOLUTION: A cooling device 300 cools a recording medium P passing through a nip part of a fixing device 200 provided in an image forming apparatus 100, and has a guide member 320 that is in contact with a non-image surface of the recording medium, and a rotatable brush-like member 310 that faces the guide member and is in contact with an image surface of the recording medium P.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a cooling device for a recording medium and an image forming apparatus. [Background technology]

[0002] In electrophotographic image forming devices, unfixed toner images carried on paper are fixed to the paper by passing the paper through the nip of the fixing device and applying heat and pressure. After fixing, the paper is ejected from the paper ejection roller and stacked on the paper ejection tray, but the heat from the fixing process has accumulated in these stacked sheets. This can cause the toner on multiple sheets of paper to melt due to the accumulated heat, resulting in a blocking phenomenon in which adjacent sheets of paper stick together via the molten toner (exit paper adhesion). Summary of the Invention [Problem to be solved by the invention]

[0003] Conventionally, methods to prevent the blocking phenomenon have been to blow air toward the surface of the paper (Patent Document 1: JP 2011-191706 A) or to cool the paper by passing it between rollers capable of dissipating heat (Patent Document 2: JP 2019-101360 A). However, as production speeds increase or the number of continuous prints increases, these cooling methods become difficult to provide sufficient cooling, making it impossible to ensure a sufficient temperature reduction range for the discharged paper, and as a result, there has been a problem in that the blocking phenomenon cannot be effectively prevented.

[0004] The present invention has been made in view of the above circumstances, and has as its object to provide a cooling device that effectively prevents the blocking phenomenon of a recording medium. [Means for solving the problem]

[0005] In order to solve the above problem, the cooling device of the present invention is a cooling device that cools a recording medium that has passed through the nip portion of a fixing device provided in an image forming apparatus, and is characterized by having a guide member that contacts the non-image side of the recording medium, and a rotatable brush-like member that faces the guide member and contacts the image side of the recording medium. [Effects of the Invention]

[0006] According to the present invention, the cooling effect of the recording medium is enhanced by the guide member and the brush-like member, and the blocking phenomenon can be effectively prevented. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram illustrating the configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. [Figure 3] 1 is a cross-sectional view of a cooling device according to a first embodiment. [Figure 4A] 1A and 1B are a side view and a plan view showing the state of air blowing to the heat dissipation fins. [Figure 4B] FIG. 10 is a plan view showing the state in which air is blown to the heat dissipation fins. [Figure 5] FIG. 10 is a perspective view of a modified example of the brush roller. [Figure 6] FIG. 6 is a cross-sectional view of a cooling device according to a second embodiment. [Figure 7] FIG. 10 is a cross-sectional view of a cooling device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] The cooling device and image forming apparatus according to the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiments, and can be modified, added, modified, deleted, or otherwise altered within the scope of what one skilled in the art can conceive. Any embodiment that achieves the functions and effects of the present invention is within the scope of the present invention.

[0009] (●Image forming equipment) Fig. 1 is a diagram illustrating the schematic configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 100 shown in Fig. 1 is a tandem color printer in which image forming units that form multiple color images are arranged side by side along the extension direction of a belt. However, the present invention is not limited to this type, and can also be applied to not only printers but also copiers, facsimile machines, etc.

[0010] The image forming apparatus 100 employs a tandem structure in which photosensitive drums 20Y, 20C, 20M, and 20Bk are arranged side by side as image carriers capable of forming images corresponding to the colors separated into yellow, cyan, magenta, and black.

[0011] In the image forming apparatus 100, the visible images formed on the photosensitive drums 20Y, 20C, 20M, and 20Bk are primarily transferred to an intermediate transfer body (hereinafter referred to as a transfer belt) 11, which is an endless belt that can move in the direction of arrow A1 while facing the photosensitive drums. By performing this primary transfer process, the images of each color are superimposed and transferred, and then, by performing a secondary transfer process, they are transferred collectively onto paper P.

[0012] Around each photosensitive drum, devices are arranged for image formation processing in accordance with the rotation of the photosensitive drum. Taking photosensitive drum 20Bk, which forms black images, as a representative example, charging device 30Bk, developing device 40Bk, primary transfer roller 12Bk, and cleaning device 50Bk, which perform image formation processing in the direction of rotation of photosensitive drum 20Bk, are arranged. An optical writing device 8 is used for writing using writing light Lb, which is performed after charging.

[0013] In the superimposed transfer onto the transfer belt 11, as the transfer belt 11 moves in the A1 direction, the visible images formed on the photosensitive drums 20Y, 20C, 20M, and 20Bk are transferred and superimposed onto the same position on the transfer belt 11. For this reason, the transfer is performed with staggered timing from the upstream side to the downstream side in the A1 direction by applying a voltage to primary transfer rollers 12Y, 12C, 12M, and 12Bk disposed opposite the photosensitive drums 20Y, 20C, 20M, and 20Bk across the transfer belt 11.

[0014] The photosensitive drums 20Y, 20C, 20M, and 20Bk are arranged in this order from the upstream side in the A1 direction. The image stations are provided for forming magenta and black images, respectively.

[0015] The image forming device 100 has four image stations that perform image formation processing for each color, a transfer belt unit 10 that is arranged above and opposite each photosensitive drum 20Y, 20C, 20M, and 20Bk and that is equipped with a transfer belt 11 and primary transfer rollers 12Y, 12C, 12M, and 12Bk, a secondary transfer roller 5 that is arranged opposite the transfer belt 11 and rotates in response to and following the transfer belt 11, a belt cleaning device 13 that is arranged opposite the transfer belt 11 and cleans the transfer belt 11, and an optical writing device 8 that is arranged below and opposite these four image stations.

[0016] The optical writing device 8 is equipped with a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, and a rotating polygonal mirror as a deflection means. The optical writing device 8 is configured to emit writing light Lb corresponding to each color to each of the photoconductor drums 20Y, 20C, 20M, and 20Bk, forming electrostatic latent images on the photoconductor drums 20Y, 20C, 20M, and 20Bk. For convenience, in FIG. 1, the writing light Lb is labeled only for the image station for black images, but the same applies to the other image stations.

[0017] The image forming apparatus 100 is provided with a paper feed device 61 serving as a paper feed cassette that holds paper P to be transported toward between the photosensitive drums 20Y, 20C, 20M, and 20Bk and the transfer belt 11. Also provided is a pair of registration rollers 4 that feeds out the paper P transported from the paper feed device 61 toward a transfer section between each photosensitive drum and the transfer belt 11 at a predetermined timing that matches the timing of toner image formation by the image station. Also provided is a sensor that detects when the leading edge of the paper P reaches the pair of registration rollers 4.

[0018] The image forming apparatus 100 is also provided with a roller fixing type fixing device 200 for fixing the toner image onto the paper P onto which the toner image has been transferred, and discharge rollers 7 for discharging the fixed paper P to the outside of the main body of the image forming apparatus 100. A cooling device 300 for cooling the discharged paper is provided upstream of the discharge rollers 7, as will be described later.

[0019] Furthermore, an output tray 17 is provided at the top of the main body of the image forming apparatus 100 to hold paper P discharged to the outside of the main body of the image forming apparatus 100 by the discharge roller 7. Toner bottles 9Y, 9C, 9M, and 9Bk filled with toner of each color, yellow, cyan, magenta, and black, are provided below the output tray 17. In addition to the transfer belt 11 and primary transfer rollers 12Y, 12C, 12M, and 12Bk, the transfer belt unit 10 also has a drive roller 72 and a driven roller 73 around which the transfer belt 11 is wound.

[0020] The driven roller 73 also functions as a tension applying means for the transfer belt 11, and for this reason, a spring or other such applying means is provided on the driven roller 73. The transfer belt unit 10, the primary transfer rollers 12Y, 12C, 12M, and 12Bk, the secondary transfer roller 5, and the cleaning device 13 constitute a transfer device 71.

[0021] The paper feed device 61 is disposed at the bottom of the main body of the image forming apparatus 100, and has a feed roller 3 that contacts the upper surface of the uppermost sheet of paper P. The feed roller 3 is driven to rotate counterclockwise in the drawing, thereby feeding the uppermost sheet of paper P toward the pair of registration rollers 4.

[0022] Although not shown in detail, the cleaning device 13 provided in the transfer device 71 has a cleaning brush and a cleaning blade disposed to face and contact the transfer belt 11. The cleaning device 13 uses the cleaning brush and cleaning blade to scrape off and remove foreign matter such as residual toner on the transfer belt 11, thereby cleaning the transfer belt 11. The cleaning device 13 also has a discharge means for carrying out and discarding the residual toner removed from the transfer belt 11.

[0023] (● Fixing device) 2 is a schematic diagram of the fixing device 200. The fixing device 200 includes a fixing belt 201 as a rotatable endless belt-like fixing member, and a pressure roller 203 as a pressure member that forms a nip portion N between the fixing belt 201 and the fixing member 201.

[0024] Inside the fixing member 201, there are arranged heat sources 202A and 202B such as halogen heaters that heat the fixing member 201, a non-rotating nip forming member 206, and a heat transfer assisting member 216 that assists in the heat transfer of the fixing member 201. The pressure roller 203 is arranged opposite the nip forming member 206 and forms a nip portion N with the fixing belt 201 sandwiched therebetween.

[0025] Then, fixing is performed by passing the sheet P carrying the unfixed image through the nip portion N. In this embodiment, the surface of the heat transfer assistance member 216 that directly contacts the fixing belt 201 becomes the nip forming surface.

[0026] The fixing belt 201 is directly heated by radiant heat from the inner periphery side by a plurality of heat sources 202A and 202B. In addition, temperature sensors 230A and 230B are attached to detect the temperature of fixing belt 201 in a non-contact manner, and the lighting rates of heat sources 202A and 202B are controlled based on the detected temperature, thereby controlling the temperature of fixing belt 201 to the desired temperature.

[0027] That is, the control means controls the heat generation (power supply to the heat sources) of the heat sources 202A, 202B so that the temperatures detected by the temperature sensors 230A, 230B reach predetermined detection target temperatures. Hereinafter, when there is no need to distinguish between the multiple heat sources, they will simply be referred to as "heat source 202."

[0028] 2, there are provided inside the fixing belt 201 a nip forming member 206 disposed opposite the pressure roller 203, a heat transfer assisting member 216 covering the surface of the nip forming member 206 facing the inner surface of the fixing belt 201, and a stay member 207 that holds the nip forming member 206 against the pressure from the pressure roller 203. The nip forming member 206 forms a nip portion N between the fixing belt 201 and the pressure roller 203, and slides indirectly against the inner surface of the fixing belt via the heat transfer assisting member 216. By passing a sheet of paper P carrying a toner image through the nip portion N, the toner on the recording medium is melted by heat and fixed to the recording medium by pressure.

[0029] A sliding coating with a low coefficient of friction is applied to the contact surface of heat transfer assist member 216 with fixing belt 201. Examples of the sliding coating include a fluorine coating and a glass coating such as DLC (diamond-like carbon) that has high abrasion resistance.

[0030] Furthermore, a lubricant is applied to the contact surface of heat transfer assisting member 216 with fixing belt 201. Suitable lubricants are fluorine grease or silicone oil, which have a high heat resistance temperature. Fluorine grease is a gel-like lubricant made by dispersing a thickener in fluorine oil, which serves as a base oil, and because it has a higher viscosity than oil, it is effective as a countermeasure against leakage from sliding parts.

[0031] The heat transfer assisting member 216 is provided to prevent heat from accumulating locally and to actively transfer heat in the longitudinal direction, thereby reducing temperature non-uniformity in the longitudinal direction. For this reason, the material for the heat transfer assisting member 216 is preferably a material that allows heat to be transferred in a short time, such as copper, aluminum, or silver, which have high thermal conductivity. Of these, copper is most preferable when cost, availability, thermal conductivity, and processability are all taken into consideration.

[0032] The fixing belt 201 is made of a metal belt such as nickel or SUS, or an endless belt or film made of a resin material such as polyimide. The surface of the belt has a release layer such as a PFA or PTFE layer to provide release properties to prevent toner from adhering. An elastic layer made of a silicone rubber layer or the like may be provided between the belt substrate and the PFA or PTFE layer.

[0033] Without the silicone rubber layer, the heat capacity is reduced and the fixing performance is improved, but when the unfixed image is crushed and fixed, the minute irregularities on the belt surface are transferred to the image, which can cause a problem in that the solid parts of the image have an uneven gloss (a citrus peel image) similar to that of a citrus peel. To improve this, a silicone rubber layer of 100 μm or more is required. The deformation of the silicone rubber layer absorbs the minute irregularities, improving the citrus peel image.

[0034] As described above, a sliding coating can be applied to the surface of the fixing belt 201 that slides against the heat transfer assisting member 216. In this case, a sliding coating material such as polyimide or polyamideimide can be selected taking into consideration heat resistance and abrasion resistance.

[0035] The stay member 207 has a shape with an upright portion on the nip portion N side and the opposite side, and heat sources 202A and 202B are arranged across the upright portion, and the fixing belt 201 is directly heated by radiant heat from the inner surface side by the heat source 202 in areas other than the nip portion.

[0036] Inside fixing belt 201, stay member 207 is provided as a support member for supporting nip forming member 206 and nip portion N, preventing bending of nip forming member 206 when pressure is applied by pressure roller 203 and ensuring a uniform nip width in the axial direction. Stay member 207 is held and fixed at both ends by flanges that serve as holding members. In addition, reflective member 209 is provided between heat source 202 and stay member 207 to prevent unnecessary energy consumption caused by the stay member 207 being heated by radiant heat from heat source 202.

[0037] Furthermore, by providing the reflecting member 209, the heaters are prevented from heating each other's glass tubes, thereby enabling efficient heating of the fixing belt 201. The reflecting member 209 is made of a material with low emissivity so as not to absorb the heat from the heat source 202. Note that, instead of providing the reflecting member 209, the same effect can be achieved by insulating or mirror-finishing the surface of the stay member 207.

[0038] The pressure roller 203 is made by covering the outer periphery of a core metal 205 with an elastic rubber layer 204, and to ensure releasability, a release layer (PFA or PTFE layer) is provided on the surface of the elastic rubber layer 204. The pressure roller 203 rotates by receiving a driving force transmitted via gears from a driving source such as a motor provided in the image forming apparatus 100.

[0039] The pressure roller 203 is pressed against the fixing belt 201 by a spring or the like, and has a predetermined nip width as the elastic rubber layer 204 is crushed and deformed. The pressure roller 203 may be a hollow roller, and may have a heat source such as a halogen heater.

[0040] The elastic rubber layer 204 may be solid rubber, but sponge rubber may also be used if there is no heater inside the pressure roller 203. Sponge rubber is more preferable because it has better heat insulation properties and is less likely to lose heat from the fixing belt.

[0041] Fixing belt 201 rotates together with pressure roller 203. In the case of FIG. 2, pressure roller 203 is rotated by a drive source, and a driving force is transmitted to the belt at nip portion N, causing fixing belt 201 to rotate. Fixing belt 201 rotates while being sandwiched at nip portion N, and runs outside the nip portion while being guided by flanges at both ends. With the above-described configuration, it is possible to realize a fixing device that is inexpensive and has a fast warm-up time.

[0042] (● Cooling device of first embodiment) 3 is a cross-sectional view of a cooling device 300 according to a first embodiment for cooling a recording medium, such as a paper sheet P. The cooling device 300 is disposed between a conveying roller 6 and a discharge roller 7, which are disposed downstream of the fixing device 200.

[0043] Cooling device 300 has brush roller 310 as a brush-like member that contacts the image side of paper P, metal guide plate 320 as a guide member that contacts the non-image side of paper P and functions as a transport guide as well as cooling paper P, and heat dissipation fins 330 arranged on the upper surface of guide plate 320. Brush roller 310 lightly presses paper P against lower surface 320a of guide plate 320, improving the contact condition (heat transfer efficiency) of paper P with guide plate 320 and preventing paper P from blocking in discharge tray 17.

[0044] The guide plate 320 can be made of a thermally conductive metal with a large heat capacity to enhance the cooling effect of the paper P. For example, the guide plate 320 can be made of SECC (bonded steel plate), aluminum, or stainless steel.

[0045] Brush roller 310 is rotated at the same speed as the paper discharge speed or slightly faster (for example, 1 to 10% faster) than the paper discharge speed so as not to impose a load on the transport of paper P. By bringing high-temperature paper P after fixing into direct contact with metal guide plate 320, which has a large heat capacity and high thermal conductivity, and dissipating heat upward, even paper transported at high speed can be cooled more quickly and effectively.

[0046] Furthermore, by providing heat dissipation fins 330 on the upper surface of metal guide plate 320 and further providing an air blower for cooling heat dissipation fins 330, guide plate 320 that has become hot due to heat storage can be quickly cooled by heat dissipation from heat dissipation fins 330. This makes it possible to efficiently and continuously cool paper P.

[0047] The tips of the bristles of brush roller 310 easily deform (bend) to softly contact the image side of paper P, ensuring a wide contact width with guide plate 320 even with light pressure. This promotes heat transfer to guide plate 320, allowing for a greater temperature drop in paper P than conventional methods for cooling during discharge. In addition, because brush fibers 312 of brush roller 310 are soft, good paper transport is possible without roughening the fixed image even when pressure is applied to the image side of paper P.

[0048] The brush roller 310 can be configured by directly implanting brush fibers 312 onto a core metal 311. The implantation density, fiber diameter, fiber type, and brush fiber penetration amount are not particularly limited and can be selected appropriately.

[0049] Examples of the type of fiber used for the brush fibers 312 include, but are not limited to, nylon, acrylic, polyester, etc. Heat-resistant polyimide resin, aramid resin, etc. can also be used for the brush fibers 312. Alternatively, as shown in FIG. 5 (described later), the brush roller 310 can be configured by spirally winding brush cloth 313 made of polyimide fibers, aramid fibers, etc., on a core metal 311. The width of the brush cloth 313 is not limited to the form shown in FIG. 5, and the width may be widened until adjacent strips come into close contact with each other so that the brush fibers spread across the entire width of the roller.

[0050] Brush roller 310 can be configured with a diameter of, for example, 30 to 35 mm and a bristle length of, for example, 5 to 10 mm, thereby ensuring a width (nip width) of 10 mm or more in the conveying direction when brush roller 310 contacts guide plate 320. The nip width of 10 mm is sufficient to ensure good paper conveyance and favorable conditions for paper cooling.

[0051] The pressing pressure of the brush roller 310 against the paper P is 100 gf / cm due to the elastic force of the brush fibers themselves. 2 This 100gf / cm 2 This pressure is suitable for pressing paper P tightly against guide plate 320. In order to stabilize the brush pressing pressure over a long period of time, it is possible to adopt a configuration in which brush roller 310 is rotatably held by a bearing and biased toward guide plate 320 by a pressing member such as a spring.

[0052] 3, brush roller 310 is driven to rotate counterclockwise at a speed equal to or faster than the conveyance speed of paper P. Brush fibers 312 can be made of low-wear fluororesin, for example, in addition to the polyimide resin and aramid resin mentioned above. Also, the same low-wear effect can be achieved by making the main body of brush fibers 312 out of heat-resistant resin or metal and applying a low-wear coating such as fluororesin to the surface of the resin or metal that comes into contact with paper P.

[0053] As shown in Fig. 3, the heat of the high-temperature paper P after fixing is transferred (not through air, which has a low thermal conductivity) directly to the metal guide plate 320, which has a high thermal conductivity, while ensuring a wide contact area, so the temperature can be reduced more than with conventional methods to cool the paper as it is discharged. The effectiveness of this cooling effect can be further enhanced by adding the arc shape of the guide plate 320 shown in Fig. 6, which will be described later, or the air blowing structure shown in Fig. 7.

[0054] (● Airflow to the heat dissipation fins) Fig. 4A shows the relationship between the direction of the ribs of the heat dissipation fin 330 and the direction of airflow in Fig. 3. As shown in Fig. 4A(a) and (b), the ribs of the heat dissipation fin 330 extend in the axial direction of the brush roller 310. Therefore, it is preferable that the airflow toward the heat dissipation fin 330 be blown from diagonally above both ends of the heat dissipation fin 330 in the longitudinal direction toward the center of the brush roller 310 in the axial direction.

[0055] 4B shows an example in which the ribs of the heat dissipation fin 330 are formed in a direction (paper transport direction) perpendicular to the axial direction of the brush roller 310. In this case, it is preferable to blow air in the paper transport direction toward the heat dissipation fin 330. Because the air inside the machine naturally flows toward the outside of the machine in the paper transport direction, the cooling effect can be improved by arranging the ribs as shown in FIG. 4B.

[0056] (●Modified brush roller) 5 shows a modified example of a brush roller 310 in which a brush cloth 313 is spirally arranged around a core metal 311. The brush cloth 313 is made by implanting polyimide fibers, aramid fibers, or the like into a belt-shaped base fabric. The spiral pitch is optional and can be, for example, 3 to 10 mm.

[0057] By arranging the brush cloth 313 in a spiral shape, the contact of the brush cloth 313 with the paper P can be made softer, and even with light pressure, a wide contact width with the guide plate 320 can be ensured. Also, when air holes 314a are formed in the core metal 311 as shown in Figure 7 described below, more air holes 314a can be formed between the pitches of the brush cloth 313.

[0058] (● Cooling device of second embodiment) 6 is a cross-sectional view of a cooling device 300 according to a second embodiment of the present invention. A guide plate 320 of this cooling device 300 is curved in an arc shape along the outer periphery of a brush roller 310. That is, a lower surface 320b of the guide plate 320 has a concave curved surface that follows the outer periphery of the brush roller 310. Furthermore, heat dissipation fins 330 are arranged along the convex upper surface of the guide plate 320.

[0059] Because the lower surface 320b of the guide plate 320 has a concave curved surface, the contact length between the guide plate 320 and the paper P is increased compared to the first embodiment of Figure 3, and the extended paper length increases the cooling effect of the paper P and also increases the temperature reduction range.

[0060] In addition, the concave curved surface of the guide plate 320 allows the paper P to change direction smoothly, and the contact pressure between the paper P and the brush fibers 312 can be equalized and reduced across the nip width, which, combined with the equal transport force of the paper P across the nip width, prevents the fixed image from becoming rough.

[0061] (● Cooling device of third embodiment) 7 is a cross-sectional view of a cooling device 300 according to a third embodiment of the present invention. The core 314 of this cooling device 300 is hollow, and an air passage 316 is formed inside the core 314. A large number of air holes 314a communicating with the air passage 316 are formed on the surface of the core 314. The brush fibers 312 are planted at positions that avoid the air holes 314a.

[0062] A blower is connected to one axial end of core metal 314, and air blown from the blower is configured to be blown radially from air holes 314a through air passage 316. The end of air passage 316 opposite to the end connected to the blower is closed with a plug.

[0063] The air blown out from the air holes 314a radially (in the direction of the white arrows in FIG. 7) to the outer periphery of the core metal 314 flows through the gaps in the brush fibers 312 toward the image surface of the paper P. This allows the paper P to be cooled even more effectively.

[0064] 7, the cooling effect can be enhanced by disposing inner circumferential guide member 315 on the inner circumferential surface of core metal 314 of brush roller 310, at a portion separated from guide plate 320. That is, inner circumferential guide member 315 has a U-shaped or horseshoe-shaped cross section, and is in sliding contact with approximately the lower half of the inner circumferential surface of core metal 314.

[0065] Air holes 314a are closed at positions where they overlap with inner circumferential guide member 315, stopping the air blowout, and are opened to resume the air blowout when they move away from inner circumferential guide member 315 and face upward. In this way, of the many air holes 314a, more than half of the lower part of core metal 314 can be closed by inner circumferential guide member 315, preventing unnecessary air blowout and improving the cooling effect.

[0066] Furthermore, the length of the core metal 314 can be made longer than the width of the largest sheet of paper P, and air holes 314a can be formed in the areas on both ends of the core metal 314 where there are no brush fibers 312. This allows air to be blown directly toward the underside of the sheet of paper P, improving the sheet cooling effect.

[0067] While the present invention has been specifically described above based on the embodiments, it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways within the scope of the technical concept set forth in the claims. For example, in the above embodiments, brush roller 310 is used as the brush-like member, but instead of brush roller 310, a brush belt having brush fibers implanted on the surface of an endless belt may be disposed opposite guide plate 320. [Explanation of symbols]

[0068] 3: Feeding roller 4: Registration roller pair 5: Secondary transfer roller 6: Conveyor roller 7: Discharge roller 8: Optical writing device 9Y, 9C, 9M, 9Bk: Toner bottles 10: Transfer belt unit 11: Transfer belt 12Y, 12C, 12M, 12Bk: Primary transfer rollers 13: Belt cleaning device 17: Paper output tray 20Y, 20C, 20M, 20Bk: Photosensitive drum 30Y, 30C, 30M, 30Bk: Charging device 40Y, 40C, 40M, 40Bk: Developing unit 50Y, 50C, 50M, 50Bk: Cleaning unit 61: Paper feeder 71: Transfer device 72: Drive roller 73: Driven roller 100: Image forming apparatus 200: Fixing device 201: Fixing belt (fixing member) 202: Heat source 202A, 202B: Heat source 203: Pressure roller 204: Elastic rubber layer 205: Core metal 206: Nip forming member 207: Stay member 209: Reflective member 216: Heat transfer auxiliary member 230A, 230B: Temperature sensor 300: Cooling device 310: Brush roller 311: Core metal 312: Brush fiber 313: Brush cloth 314: Core metal 314a: Air hole 315: Inner guide member 316: Air passage 320: Metal guide plate 320b: Bottom surface 330: Heat dissipation fin Lb: Writing light N: Nip P: Paper (recording medium) [Prior art documents] [Patent documents]

[0069] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-191706 [Patent Document 2] Japanese Patent Application Publication No. 2019-101360

Claims

1. A cooling device that cools a recording medium that has passed through a nip portion of a fixing device provided in an image forming apparatus with the non-image side facing up, characterized in that the cooling device has a guide member that contacts the non-image side of the recording medium, and a rotatable brush-like member that faces the lower surface of the guide member and contacts the image side of the recording medium.

2. 2. The cooling device according to claim 1, wherein said brush-like member is a brush roller having brush fibers planted around a core metal.

3. 3. The cooling device according to claim 2, wherein said brush roller is rotationally driven by a driving means at a speed equal to or higher than the transport speed of said recording medium.

4. 4. The cooling device according to claim 2, wherein the brush fibers of the brush roller are spirally planted around the core metal.

5. 5. The cooling device according to claim 2, wherein the guide member is made of a heat-conductive metal.

6. 6. The cooling device according to claim 2, wherein the guide member has a concave curved surface that conforms to the outer circumferential shape of the brush roller.

7. 7. The cooling device according to claim 1, further comprising an air blowing means for blowing air toward the guide member.

8. 3. The cooling device according to claim 2, wherein an air passage is formed inside the core metal of the brush roller, and the air passage communicates with the outer periphery of the brush roller through a plurality of air holes on the surface of the core metal.

9. 9. The cooling device according to claim 8, wherein an inner peripheral guide member for closing said air holes is provided on an inner peripheral surface of said core metal at a portion spaced from said guide member.

10. An image forming apparatus comprising the cooling device according to any one of claims 1 to 9.

Images