JP2007086310A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently cool and discharge a recording medium to which a toner image is fixed without causing the problem of defects or the like due to dew condensation. <P>SOLUTION: When the cooling roll 114 of high cooling capacity is used, a recording paper sheet P is sufficiently cooled. However, by a large temperature difference from surrounding air warmed by the recording paper sheet P after fixation, dew is condensed on the surface of the cooling roll 114. That is, droplets K are stuck to the surface. However, the droplets K are separated from the recording paper sheet P accompanying the rotation of the cooling roll 114 and scraped and removed by a scraper 118. The removed droplets K are accumulated at the lower part of a case 112. Thus, the problem due to the droplets K stuck to the cooling roll 114, for instance the defect due to the sticking of the droplets K to the recording paper sheet P or the like, does not arise. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  In the image forming apparatus, the toner image transferred to the recording paper is fixed on the recording paper by the heat fixing device, and is discharged onto the paper discharge tray and stacked.

  The recording paper on which the toner image has been fixed by the heat fixing device is hot. If the recording paper is stacked on the paper discharge tray before it is sufficiently cooled, heat is accumulated between the overlapping recording paper, and the fixed toner image Is sticky. For this reason, a so-called blocking phenomenon occurs that sticks to the back surface of the recording paper stacked thereon.

  In particular, in a high-speed machine, since recording sheets are discharged one after another and stacked on a discharge tray, a blocking phenomenon tends to occur. Also, when the print coverage rate is high (when the area occupied by the toner image is large), the blocking phenomenon tends to occur.

  In order to prevent such a blocking phenomenon, a configuration has been proposed in which the recording paper is cooled by sending air to the transport roll and the recording paper as in the configuration of Patent Document 1. (See Patent Document 1).

  However, even if air is sent so as to be orthogonal to the conveyance direction of the recording sheet as in the configuration of Patent Document 1 (see FIG. 3 of Patent Document 1), the cooling capacity for the recording sheet is low. . In particular, a high speed machine with a conveyance speed of about 300 mm / sec can hardly be expected. Furthermore, the behavior of the leading end of the recording paper being conveyed becomes unstable due to the blowing of air. Therefore, the leading end of the recording sheet is likely to be bent or jammed.

Therefore, a configuration in which a heat pipe is provided in the paper guide to cool the recording paper has been proposed. (For example, refer to Patent Document 2).
Japanese Patent Laid-Open No. 3-19617 JP-A-4-260065

  However, when the paper guide is cooled by a heat pipe in order to increase the cooling capacity of the recording paper as in the configuration of Japanese Patent Application Laid-Open No. 4-260065 of Patent Document 1, condensation occurs on the paper guide. That is, water droplets adhere to the paper guide. The water droplets adhere to the recording paper and cause defects such as white spots.

  The present invention has been made to solve the above problem, and an object thereof is to sufficiently cool and discharge a recording medium on which a toner image is fixed without causing problems such as defects due to condensation.

  The image forming apparatus according to claim 1, wherein an image forming unit that transfers a toner image to a recording medium, and a thermal fixing unit that fixes the toner image transferred to the recording medium by the image forming unit to the recording medium. And a discharge section for discharging the recording medium on which the toner image has been fixed by the heat fixing section, and a conveyance path section between the fixing section and the discharge section, for conveying and cooling the recording medium. Conveying cooling means, and the conveying cooling means abuts on the recording medium and rotates to convey the recording medium and to generate a rotation cooling member that cools the recording medium and the rotating cooling member The dew condensation removing means for removing the condensed dew, and the dew condensation capturing means for capturing the dew condensation removed by the removing means.

  In the image forming apparatus according to the first aspect, the toner image transferred to the recording medium by the image forming unit is fixed by the heat fixing unit. The recording medium on which the toner image has been fixed by the heat fixing unit is conveyed and cooled by a rotation cooling member provided in the conveyance path unit, and is discharged from the discharge unit.

  Therefore, after the recording medium is sufficiently cooled, it is stacked on the discharge portion, so that the blocking phenomenon does not occur.

  Now, since the rotary cooling member sufficiently cools the recording medium, there is a large temperature difference with the surrounding air heated by the recording medium having heat after fixing. For this reason, the rotating cooling member is condensed. However, the condensation is removed by the condensation removing means, and the condensation (water droplets) removed by the condensation capturing means is captured.

  Therefore, problems caused by condensation, such as a defect caused by water droplets adhering to the recording medium, do not occur.

  According to a second aspect of the present invention, in the configuration of the first aspect, the rotation cooling member is in contact with a surface of the recording medium on which the toner image is fixed.

  In the image forming apparatus according to the second aspect, since the rotation cooling member contacts the surface of the recording medium on which the toner image is fixed, the cooling effect on the fixed toner image is high.

  According to a third aspect of the present invention, there is provided the image forming apparatus according to the first or second aspect, wherein a plurality of the rotation cooling members are arranged in the conveyance direction of the recording medium.

  Since the image forming apparatus according to the third aspect is cooled by a plurality of rotating cooling members arranged in the conveyance direction of the recording medium, the cooling capacity is remarkably high. Further, since the cooling is gradually performed in order, the uneven gloss is reduced.

  According to a fourth aspect of the present invention, in the configuration according to any one of the first to third aspects, the conveyance cooling unit includes a blower unit that cools the rotary cooling member. Yes.

  In the image forming apparatus according to the fourth aspect, since the blowing unit cools the rotating cooling member, the cooling capacity of the rotating cooling member is improved.

  In addition, by preventing the air sent by the blowing unit from hitting the recording medium being conveyed, the recording medium being conveyed does not cause a conveyance failure.

  According to a fifth aspect of the present invention, in the configuration according to the fourth aspect, the air blowing unit blows air to the recording medium discharged to the discharge unit.

  In the image forming apparatus according to the fifth aspect, air is blown to the recording medium discharged to the discharge portion by the blower, so that the recording medium is cooled even after the discharge. Therefore, the blocking phenomenon is further prevented.

  According to a sixth aspect of the present invention, in the configuration according to any one of the first to fifth aspects, the rotary cooling member is a cooling roll.

  According to a sixth aspect of the present invention, the recording medium is conveyed and cooled by the cooling roll.

  According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, the cooling roll is made of metal.

  According to a seventh aspect of the present invention, the recording medium is conveyed and cooled by a metal cooling roll. Since the metal cooling roll has good thermal conductivity, the cooling capacity is high.

  An image forming apparatus according to an eighth aspect is characterized in that, in the configuration according to the seventh aspect, the metal cooling roll is a cylinder.

  An image forming apparatus according to an eighth aspect transports and cools the recording medium with a cylindrical metal cooling roll. The cylindrical metal cooling roll has a high cooling capacity because it has a high thermal conductivity and a large heat capacity.

  According to a ninth aspect of the present invention, in the configuration according to the seventh aspect, the metal cooling roll is hollow and has cooling fins on the inner wall.

  According to a ninth aspect of the present invention, the inner wall includes a cooling fin. Therefore, since the cooling roll is radiated by the cooling fins, the cooling capacity is improved.

  According to a tenth aspect of the present invention, in the configuration according to the ninth aspect, the cooling fin is a spiral fin that generates an axial air flow inside the cooling roll as the cooling roll rotates. It is characterized by being.

  In the image forming apparatus according to the tenth aspect, since the spiral fin generates an air flow in the axial direction inside the cooling roll as the cooling roll rotates, the heat radiation effect is further enhanced. Therefore, the cooling capacity of the cooling roll is further improved.

  The image forming apparatus according to claim 11 is the configuration according to claims 1 to 10, wherein the recording medium having the toner image fixed on one side is reversed, and the recording medium is again recorded on the image forming unit. The reversal conveyance unit is also provided with the conveyance cooling means.

  In the image forming apparatus according to the eleventh aspect, since the reversal conveyance unit also includes the conveyance cooling unit, the recording medium is cooled when the toner image is transferred to the other surface by the image formation unit. Therefore, the transfer of the toner image to the recording medium is stabilized.

  According to a twelfth aspect of the present invention, in the configuration according to the eleventh aspect, the first reversing conveyance unit reverses the recording medium having the toner image fixed on one side thereof, and then conveys the recording medium to the image forming unit. It is also possible to carry it to the carrying part without doing so.

  The image forming apparatus according to claim 12, the recording medium having the toner image fixed on one side is cooled by the reverse conveyance unit and reversed upside down, and then conveyed to the conveyance unit without being conveyed to the development unit, and cooled. It can also be discharged to the discharge section. That is, the recording medium can be cooled by both the conveyance cooling unit of the reverse conveyance unit and the conveyance cooling unit of the conveyance unit. Therefore, the cooling efficiency is remarkably high.

  As described above, according to the present invention, the recording medium on which the toner image is fixed can be sufficiently cooled and discharged without causing problems such as defects due to condensation.

  FIG. 1 shows an image forming apparatus 100 according to the first embodiment of the present invention.

  The image forming apparatus 100 performs image processing based on color image information sent from an image data input device such as a personal computer (not shown), and forms a color image on the recording paper P by an electrophotographic method. The image forming apparatus 100 is a high-speed machine having a conveyance speed of about 300 mm / sec.

  The image forming apparatus 100 includes an image forming unit 102, a paper feeding unit 104, and a paper discharge unit 106.

  The image forming unit 102 includes image forming units 10Y, 10M, 10C, and 10K that form toner images of respective colors of yellow (Y), magenta (M), cyan (C), and black (K). In the following, when it is necessary to distinguish YMCK, any of Y, M, C, and K is added after the sign, and when it is not necessary to distinguish YMCK, Y, M, C, and K are omitted. To do.

  The image forming units 10 </ b> Y, 10 </ b> M, 10 </ b> C, and 10 </ b> K are arranged in a line in the traveling direction W of the endless intermediate transfer belt 30 stretched by the backup roll 34 and the plurality of stretch rolls 32. Further, the intermediate transfer belt 30 is disposed to face the photosensitive drums 12Y, 12M, 12C, and 12K as latent image carriers of the image forming units 10Y, 10M, 10C, and 10K, and the photosensitive drums 12, respectively. The primary transfer rolls 16Y, 16M, 16C, and 16K are inserted.

  Next, the configuration of each of the image forming units 10Y, 10M, 10C, and 10K and the image forming operation on the intermediate transfer belt 30 will be described as a representative of the image unit 10Y that forms a yellow toner image.

  First, the surface of the photosensitive drum 12Y is uniformly charged by the charger 13Y. Next, image exposure corresponding to the yellow image is performed by the exposure device 14Y, and an electrostatic latent image corresponding to the yellow image is formed on the surface of the photosensitive drum 12Y.

  The electrostatic latent image corresponding to the yellow image is developed by the developing device 15Y to become a yellow toner image. The yellow toner image is transferred onto the intermediate transfer belt 30 by electrostatic attraction by a transfer bias applied to the primary transfer roll 16Y. After the primary transfer, the untransferred residual yellow toner remaining on the photosensitive drum 12Y is removed by the photosensitive drum cleaning device 17Y. The surface of the photosensitive drum 12Y is neutralized by a static eliminator (not shown) and then charged again by the charger 13Y for the next image forming cycle.

  In the image forming apparatus 100, the image forming process similar to the above is performed at the timing in consideration of the relative positions of the image forming units 10Y, 10M, 10C, and 10K, and the image forming units 10Y, 10M, 10C, and 10K. The toner images of Y, M, C, and K are sequentially superimposed on the intermediate transfer belt 30 to form a full color toner image.

  The full-color toner image formed on the intermediate transfer belt 30 is in contact with a backup roll 34 that supports the intermediate transfer belt 30 on a recording paper P that is conveyed to the secondary transfer position A at a predetermined timing. The image is transferred by an electrostatic attraction force due to a transfer bias applied to.

  The recording paper P is stored in the paper feed cassettes 60 and 61 of the paper feed unit 104 disposed on the side of the image forming unit 102. Then, the recording paper P is fed from one of the paper feed cassettes 60 and 61 to the image forming unit 102. The fed recording paper P is sent to the secondary transfer position A at a predetermined timing by a plurality of transport rolls 66 and registration rolls 68 of the transport mechanism 64. As described above, the full-color toner images are collectively transferred from the intermediate transfer belt 30 to the recording paper P by the backup roll 34 and the secondary transfer roll 36.

  The untransferred residual toner on the intermediate transfer belt 30 that has not been transferred to the recording paper P by the backup roll 34 and the secondary transfer roll 36 is scraped off and removed by the cleaning blade 42 of the intermediate transfer belt cleaning device 40. The

  The recording paper P on which the full-color toner image is transferred from the intermediate transfer belt 30 is separated from the intermediate transfer belt 30 and is then transferred to the fixing device 50 by the conveyance belt 38 disposed on the downstream side of the secondary transfer position A. Be transported.

  The fixing device 50 includes a heat fixing roll 52 including a heat source such as a halogen lamp inside a metal core having high thermal conductivity. Further, a nip is formed on the heat fixing roll 52 of the pressure roll 56 that is paired with the heat fixing roll 52.

  The surface carrying the full-color toner image becomes the heat-fixing roll 52 side, and when the recording paper P is gripped and conveyed by the heat-fixing roll 52 and the pressure roll 56, the full-color toner image is formed by heat and pressure. Fix to recording paper P.

  The recording paper P on which the color toner image is fixed by the fixing device 50 is sent to the paper discharge unit 106. Then, the recording paper P is discharged to the paper discharge tray 72 by the paper discharge mechanism 110 of the paper discharge unit 106 and stacked. Details of the paper discharge mechanism 110 will be described later.

  Now, the image forming apparatus 100 inverts the front and back of the recording paper P on which the color toner image is fixed on one side, conveys the recording paper P to the secondary transfer position A again, and intermediates the other side as well. A new full color toner image is transferred from the transfer belt 30 and an image can be formed on both sides of the recording paper P.

  Specifically, the recording paper P is reversed by the reverse conveyance mechanism 70 of the paper discharge unit 106, and then conveyed to the conveyance mechanism 64 via the reverse conveyance path 74. The recording paper P is again recorded at a predetermined timing by the conveyance mechanism 64. The other surface of P becomes the intermediate transfer belt 30 side and is sent to the secondary transfer position A.

  Then, after the full color toner image is transferred to the other side of the recording paper P, the color toner image is similarly fixed to the other side by the fixing device 50, and this time the paper discharge mechanism 110 of the paper discharge unit 106. The paper is discharged to the paper discharge tray 72.

  Next, the paper discharge mechanism 110 will be described.

  As shown in FIG. 2, the paper discharge mechanism 110 includes a box-shaped case 112, and a metal cylinder (non-hollow rod-shaped) cooling roll 114 as a rotation cooling member is rotatably supported on the case 112. Has been. Note that a plurality (five in this embodiment) of the cooling rolls 114 are arranged in parallel in the conveyance direction S of the recording paper P. Further, the case 112 is inclined in the transport direction S of the recording paper P. Further, a plurality of holes 116 are formed in the bottom surface (slope) of the case 112, and the cooling roll 114 is exposed from the holes 116.

  A pair of drive rolls 180 nip each cooling roll 114. The driving roll 180 is rotated by a driving mechanism (not shown), and the cooling roll 114 is also rotated by the rotation of the driving roll 180. The recording paper P is gripped and conveyed by the drive roll 180 and the cooling roll 114.

  Further, in the case 112, a scraper 118 fixed to the fixing member 115 is in contact with the cooling roll 114. For the scraper 118, a rubber blade such as urethane or silicon, a metal plate, or the like is used. In FIG. 1, illustration of the fixing member 115 and the scraper 118 is omitted.

  Next, the operation of this embodiment will be described.

  As shown in FIG. 1, the recording paper P on which the full color toner image is transferred from the intermediate transfer belt 30 is separated from the intermediate transfer belt 30, and then is conveyed by a conveyance belt 38 disposed downstream of the secondary transfer position A. It is conveyed to the fixing device 50. When the recording paper P sent to the fixing device 50 is gripped and conveyed by the heat fixing roll 52 and the pressure roll 56, the full color toner image is fixed on the recording paper P by heat and pressure. The recording paper P on which the color toner image is fixed by the fixing device 50 is sent to the paper discharge unit 106.

  As shown in FIG. 2, the recording paper P sent to the paper discharge unit 106 is gripped and conveyed by the cooling roll 114 and the drive roll 180 of the paper discharge mechanism 110. At this time, the surface on which the recording paper P contacts the cooling roll 114 is the surface on which the full-color toner image is fixed.

  Then, while the recording paper P is gripped and conveyed by the cooling roll 114 and the driving roll 180, the heat of the recording paper P is taken away by the cooling roll 114, and the recording paper P is rapidly and sufficiently cooled.

  Therefore, after the recording paper P is sufficiently cooled, it is discharged onto the paper discharge tray 72 as shown in FIG. Therefore, the recording paper P is not curled. Further, since the recording paper P is sufficiently cooled, the blocking phenomenon does not occur even when the recording paper P is stacked and overlapped on the paper discharge tray 72.

  In addition, the metal cylindrical cooling roll 114 has a good heat conductivity and a large heat capacity, and thus has a high cooling capacity. Further, the cooling capacity is remarkably increased by gradually cooling the plurality of cooling rolls 114 in order. In addition, uneven gloss of the toner image can be suppressed.

  When the cooling roll 114 having such a high cooling capacity is used, the recording paper P can be sufficiently cooled. However, as shown in FIG. 2, the surface of the cooling roll 114 is condensed due to a large temperature difference from the surrounding air heated by the recording paper P having heat after fixing. That is, water droplets K adhere to the surface.

  However, the water droplet K moves away from the recording paper P as the cooling roll 114 rotates, and is scraped and removed by the scraper 118. The removed water droplet K accumulates at the bottom of the case 112. Therefore, problems due to the water droplets K adhering to the cooling roll 114, for example, defects due to the water droplets K adhering to the recording paper P do not occur.

  In this way, the water droplets K adhering to the surface are removed by the scraper 118 and accumulated in the lower portion of the case 112, so that the recording paper P is cooled sufficiently in order to sufficiently cool the recording paper P, which is a metal cylinder (non-hollow bar) cooling roll 114. Can be used.

  Since the amount of water droplets K adhering to the cooling roll 114 is small, the amount of water droplets K collected at the lower part of the case 112 is also small. Therefore, it will not evaporate naturally.

  Although not shown, an absorbent body such as a sponge may be provided at the lower portion of the case 112 to absorb the water droplets K so that the device does not leak out of the case 112 even if the apparatus is tilted or vibrated. Or you may provide the mechanism discharged | emitted out of an apparatus with a pump etc.

  Since the cooling roll 114 rotates as described above, the water droplets K can be easily removed by bringing the scraper 118 into contact therewith. However, for example, when cooling is performed with a fixed guide or the like that only contacts the recording medium, it is very difficult to remove the attached water droplets K.

  Next, a modified example of the cooling roll will be described.

  In the first modification, as shown in FIG. 3A, the cooling roll 124 is formed with a plate-like cooling fin 126 that is long in the axial direction on the inner wall of a cylindrical hollow metallic pipe.

  With such a configuration, the cooling roll 124 of the first modification has a large surface area due to the cooling fins 126, and the cooling fins 126 come into contact with the air with rotation, so that the heat radiation effect is great. Therefore, since the cooling roll 124 dissipates heat and the temperature decreases, the cooling capacity is high.

  In the second modified example, as shown in FIG. 3B, the cooling roll 134 has a spiral fin 136 formed in a spiral shape on the inner wall of the pipe. Therefore, along with the rotation of the cooling roll 134, the spiral fin 136 generates an air flow that flows in the axial direction inside the cooling roll 134.

  Since it was set as such a structure, in addition to the effect of the 1st modification, since the air flow of an axial direction generate | occur | produces with the rotation of the cooling roll 134 of a 2nd modification, the heat dissipation effect is still higher. Therefore, the cooling roll 134 is further dissipated and the temperature is lowered, so that the cooling capacity is also increased.

  Next, an image forming apparatus according to a second embodiment of the present invention will be described.

  FIG. 4 shows an image forming apparatus 200 according to the second embodiment of the present invention. The image forming apparatus 200 includes an image forming unit 102, a paper feed unit 104, and a paper discharge unit 206.

  Note that the image forming unit 102 and the paper feeding unit 104 have the same configurations as those in the first embodiment, and thus description thereof is omitted. Also, the description of the same configuration and members as those described in the first embodiment is omitted for the paper discharge unit 206.

  The paper discharge unit 206 includes a paper discharge mechanism 210 that conveys the recording paper P on which the full-color toner image is fixed.

  As shown in FIG. 5, the paper discharge mechanism 210 includes a box-shaped case 212, and a plurality of metal cylindrical cooling rolls 114 are rotatably supported on the case 212. Further, the case 212 is inclined in the conveyance direction S of the recording paper P. Further, a plurality of holes 216 are formed in the bottom surface (slope) of the case 212, and the cooling roll 114 is exposed from the holes 216. A pair of drive rolls 180 nip each cooling roll 114. The driving roll 180 is rotated by a driving mechanism (not shown), and the cooling roll 114 is also rotated by the rotation of the driving roll 180. The recording paper P is gripped and conveyed by the drive roll 180 and the cooling roll 114. Inside the case 212, the scraper 118 fixed to the fixing member 115 is in contact with the cooling roll 114. In FIG. 4, illustration of the fixing member 115 and the scraper 118 is omitted.

  Furthermore, a cooling fan 220 that blows air in the same direction as the recording paper P transport direction S is attached to the upstream end of the case 212 in the transport direction S of the recording paper P.

  The air sent by the cooling fan 220 is blown to each cooling roll 114 as indicated by an arrow R1. Further, as indicated by an arrow R 2, the paper is blown out from the discharge port 212 A opened at the downstream end portion in the transport direction S of the case 212 and blown onto the recording paper P discharged to the paper discharge tray 72.

  Further, as shown in FIG. 4, some of the rolls of the reverse conveying mechanism 170 of the paper discharge unit 206 are also metal cylindrical cooling rolls 114.

  As shown in FIG. 6, similarly, a plurality of metal cylindrical cooling rolls 114 are rotatably supported by a box-shaped case 252. A plurality of holes 254 are formed on both side surfaces of the case 252, and the cooling roll 114 is exposed from the holes 254. A pair of drive rolls 180 nip each cooling roll 114. The driving roll 180 is rotated by a driving mechanism (not shown), and the cooling roll 114 is also rotated by the rotation of the driving roll 180. The recording paper P is gripped and conveyed by the drive roll 180 and the cooling roll 114. Inside the case 252, a scraper 258 fixed to the fixing member 256 is in contact with the cooling roll 114.

  Further, as shown in FIG. 4, the reverse transport mechanism 170 reverses the recording paper P from the front and back, and then transports the recording paper P to the paper discharge mechanism 210 via the transport path 76 without being sent to the reverse transport path 74. It is also possible to discharge to 72.

  Next, the operation of this embodiment will be described.

  As described above, the recording paper P on which the color toner image is fixed by the fixing device 50 is sent to the paper discharge unit 206.

  As shown in FIG. 5, the recording paper P sent to the paper discharge unit 206 is gripped and conveyed by the cooling roll 114 and the drive roll 180 of the paper discharge mechanism 210. Then, while the recording paper P is gripped and conveyed by the cooling roll 114 and the driving roll 180, the heat of the recording paper P is taken away by the cooling roll 114, and the recording paper P is rapidly and sufficiently cooled.

  Accordingly, the recording paper P is sufficiently cooled and then discharged onto the paper discharge tray 72. Therefore, the recording paper P is not curled. Further, since the recording paper P is sufficiently cooled, the blocking phenomenon does not occur even if the recording paper P is stacked and overlapped on the paper discharge tray 72.

  Further, even if the surface of the cooling roll 114 is condensed due to a large temperature difference from the ambient air and water droplets K adhere to the surface, they are scraped and removed by the scraper 118. The removed water droplet K accumulates at the bottom of the case 212. Therefore, problems due to water droplets adhering to the cooling roll 114, for example, defects due to the water droplets K adhering to the recording paper P do not occur.

  Furthermore, since the air blown by the cooling fan 220 is blown to the cooling roll 114, heat dissipation of the cooling roll 114 is promoted. That is, the cooling capacity of the cooling roll 114 is improved.

  Also, the wind from the cooling fan 220 blows out from the discharge port 212A opened at the downstream end of the case 212 in the transport direction S and blows onto the recording paper P discharged to the discharge tray 72 to cool it. Therefore, since the recording paper P is further cooled after being discharged to the paper discharge tray 72, the blocking phenomenon is further prevented.

  Note that the air blown from the cooling fan 220 does not hit the recording paper P being transported or is only very weak even if it hits, so that the transport failure of the recording paper P is not caused.

  As shown in FIG. 6, the reverse transport mechanism 170 also includes the same cooling roll 114, scraper 258, case 252, etc., so that it is reversed and transported to the secondary transfer position A via the reverse transport path 74. The recording paper P to be printed is also cooled. Therefore, the transfer at the secondary transfer position A is stabilized.

  Further, as shown in FIG. 4, after the recording paper P is reversed and cooled by the reverse conveying mechanism 170, the recording paper P is conveyed to the paper discharge mechanism 210 through the conveying path 76 without being sent to the reverse conveying path 74, and further recorded. It is also possible to cool the paper P and discharge it to the paper discharge tray 72.

  In this case, the cooling roll 114 of the reverse conveyance mechanism 170 comes into contact with one surface on which the toner image is fixed. Then, since the paper is reversed and sent to the paper discharge mechanism 210, the other surface (the surface opposite to the one surface) of the cooling roll 114 of the paper discharge mechanism 210 abuts. That is, the cooling roll 114 comes into contact with both surfaces of the recording paper P and cools.

  Note that, in this way, both the reverse conveyance mechanism 170 and the paper discharge mechanism 210 cool the both sides of the recording paper P. However, even if the recording paper P is always conveyed and cooled by such a conveyance path, the recording paper P is cooled. In general, the recording paper P may be cooled only by the paper discharge mechanism 210, and the recording paper P may be cooled by both the reverse conveyance mechanism 170 and the paper discharge mechanism 210 only in a specific case.

  The specific case includes a case where the print cover registration is high, a case where the recording paper P is thick, a case where the conveyance speed is high (in the case of an apparatus capable of varying the conveyance speed), and the like.

  In this embodiment, the first modified cooling roll 124 and the second modified cooling roll 134 (see FIG. 3) described in the modified example of the first embodiment may be used.

  Next, an image forming apparatus according to a third embodiment of the present invention will be described.

  FIG. 7 shows an image forming apparatus 300 according to the second embodiment of the present invention. The image forming apparatus 300 includes an image forming unit 102, a paper feed unit 104, and a paper discharge unit 306.

  Note that the image forming unit 102 and the paper feeding unit 104 have the same configurations as those in the first embodiment, and thus description thereof is omitted. The paper discharge unit 306 will not be described for the same configurations and members as those described in the first embodiment.

  The paper discharge unit 306 includes a paper discharge mechanism 310 that conveys the recording paper P on which the full-color toner image is fixed.

As shown in FIG. 8, the paper discharge mechanism 310 includes a box-shaped case 312, and a metal hollow cooling roll 314 is rotatably supported on the case 312. The case 312 is inclined in the conveyance direction S of the recording paper P. Further, a plurality of holes 316 are formed in the bottom surface (slope) of the case 312, and the cooling roll 314 is exposed from the holes 316. A pair of driving rolls 180 nip each cooling roll 314. The driving roll 180 is rotated by a driving mechanism (not shown), and the cooling roll 314 is also rotated by the rotation of the driving roll 180. The recording paper P is gripped and conveyed by the drive roll 180 and the cooling roll 314. Although not shown, a scraper fixed to a fixing member is in contact with the cooling roll 314 inside the case 312 as in the first embodiment. (See Figure 2)
Further, a cooling fan 320 that sends air in the axial direction of the cooling roll 314 is attached to the side surface of the upstream end portion of the case 312 in the conveyance direction S of the recording paper P. Further, the end portions of the cooling roll 314 are connected by a duct 322. Therefore, the air sent from the cooling fan 320 passes through the cooling roll 314 and the duct 322 and is sent to the discharge duct 330 as indicated by an arrow R3.

  The discharge duct 330 is formed with a discharge port 330 </ b> A that blows air in the conveyance direction S of the recording paper P, and blows air onto the discharged recording paper P.

  FIG. 9 is a cross-sectional view taken along the line AA in FIG. 8 and shows a configuration of a coupling portion between the duct 322 and the cooling roll 314.

  A flange 340 fixed to the case 312 is fitted into the end of the cooling roll 314. A bearing 342 is provided between the inner wall of the cooling roll 314 and the flange 340. A duct 322 is provided outside the flange. The gap between the duct 322 and the flange 340 is sealed with a seal member 344 such as rubber.

  With such a configuration, the hollow cooling roll 314 can be rotatably supported and air can be passed from the duct 322 into the cooling roll 314 in the axial direction.

  Next, the operation of this embodiment will be described.

  As shown in FIG. 8, the air sent by the cooling fan 320 passes through the inside of the cooling roll 314, so that the heat release from the cooling roll 314 is promoted. That is, the cooling capacity of the cooling roll 314 is improved.

  The air blown from the cooling fan 320 is blown out from the discharge port 330A of the discharge duct 330 and blown onto the recording paper P discharged to the discharge tray 72 to be cooled. Therefore, since the recording paper P is further cooled after being discharged to the paper discharge tray 72, the blocking phenomenon is further prevented.

  In addition, this invention is not limited to the said embodiment.

  For example, in the above embodiment, the recording paper P is cooled by the cooling rolls 114, 124, 134, and 314, but the present invention is not limited to this.

  For example, as shown in FIG. 10, a configuration may be adopted in which gripping and transporting is performed by a transport belt 720 that is mounted between rolls 714 and a drive belt 782 that is mounted and driven by a drive roll 780. The removal of the water droplets K may be performed by the scraper 718, and the removed water droplets K may be stored in the lower portion of the case 712.

  In the case of such a configuration, if the roll 714 is a cylindrical or hollow (tubular) metal roll and the transport belt 720 is an endless metal belt made of a thin film metal, the cooling capacity is increased.

  Furthermore, as shown by the dotted line in the figure, when the cooling member 800 made of a Peltier element or the like is cooled so as to abut against the inner wall of the conveying belt 720, the cooling capacity is remarkably increased.

  In this way, when the cooling capacity is remarkably increased by the cooling member 800, the dew condensation is very easy. However, as described above, the configuration is such that the water droplets K are removed by the scraper 718 and the removed water droplets K are stored in the lower portion of the case 712, so that problems due to condensation do not occur.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to a first embodiment of the present invention. 1 is a diagram illustrating a schematic configuration of a paper discharge mechanism of an image forming apparatus according to a first embodiment of the present invention. (A) is a figure which shows the cooling roll of a 1st modification, (B) is a figure which shows the cooling roll of a 2nd modification. It is a figure which shows schematic structure of the image forming apparatus which concerns on 2nd embodiment of this invention. FIG. 5 is a diagram illustrating a schematic configuration of a paper discharge mechanism of an image forming apparatus according to a second embodiment of the present invention. It is a figure which shows schematic structure of the inversion conveyance mechanism of the image forming apparatus which concerns on 2nd embodiment of this invention. It is a figure which shows schematic structure of the image forming apparatus which concerns on 3rd embodiment of this invention. It is a figure which shows schematic structure of the paper discharge mechanism of the image forming apparatus which concerns on 3rd embodiment of this invention. It is a figure of the AA cross section of FIG. It is a schematic block diagram which shows the paper discharge mechanism of the other example of this invention.

Explanation of symbols

50 Thermal fixing device (thermal fixing unit)
72 Discharge tray (discharge section)
DESCRIPTION OF SYMBOLS 100 Image forming apparatus 102 Image forming part 106 Paper discharge part (conveyance path part)
112 cases (condensation capture means)
114 Cooling roll (rotary cooling member)
118 Scraper (condensation removal means)
126 Cooling fin 136 Spiral fin 170 Reverse conveyance mechanism (reverse conveyance unit)
200 Image forming apparatus 212 Case (condensation capturing means)
220 Fan (Blowing means)
300 Image forming apparatus 320 Fan (air blowing means)
720 Conveyor belt (rotary cooling member)
P Recording paper (recording medium)

Claims (12)

An image forming unit that transfers a toner image to a recording medium;
A thermal fixing unit for fixing the toner image transferred to the recording medium in the image forming unit to the recording medium;
A discharge unit for discharging the recording medium on which the toner image is fixed by the thermal fixing unit;
A transport cooling unit provided in a transport path between the fixing unit and the discharge unit, for transporting and cooling the recording medium;
With
The transport cooling means includes
A rotary cooling member that contacts the recording medium and rotates to convey the recording medium and cool the recording medium;
Dew condensation removing means for removing dew condensation generated on the rotating cooling member;
Condensation trapping means for capturing the condensation removed by the condensation removal means;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the rotation cooling member contacts a surface of the recording medium on which the toner image is fixed.   The image forming apparatus according to claim 1, wherein a plurality of the rotation cooling members are arranged in a conveyance direction of the recording medium.   The image forming apparatus according to claim 1, wherein the conveyance cooling unit includes a blowing unit that cools the rotary cooling member.   The image forming apparatus according to claim 4, wherein the blowing unit blows air also onto the recording medium discharged to the discharge unit.   The image forming apparatus according to claim 1, wherein the rotary cooling member is a cooling roll.   The image forming apparatus according to claim 6, wherein the cooling roll is made of metal.   The image forming apparatus according to claim 7, wherein the metal cooling roll is a cylinder.   The image forming apparatus according to claim 7, wherein the metal cooling roll is hollow and includes a cooling fin on an inner wall.   The image forming apparatus according to claim 9, wherein the cooling fin is a spiral fin that generates an axial air flow inside the cooling roll as the cooling roll rotates. A reversing conveyance unit for reversing the recording medium on which the toner image is fixed on one side and conveying the recording medium again to the image forming unit;
11. The image forming apparatus according to claim 1, wherein the reverse conveyance unit is also provided with the conveyance cooling unit.   The reversing and conveying unit can reversely convey the recording medium having a toner image fixed on one side thereof and then convey the recording medium to the conveying unit without conveying it to the image forming unit. Item 12. The image forming apparatus according to Item 11.

Images