JP2019174682A - Image formation device - Google Patents

Abstract

To provide an image formation device that prevents condensation from adhering to recording material after fixing.SOLUTION: An image formation device includes a fixing roller 220 and a pressure roller 202 facing the fixing roller 220 across a conveyance path 3 where a recording material S is conveyed. The image formation device further includes: a discharge inlet guide 313 provided on the opposite side to the fixing roller 220 across the conveyance path 3 and between a fixing discharge roller 204 and a pre-discharge roller 206; and a sensor flag 309 for urging the recording material S conveyed between the fixing discharge roller 204 and the pre-discharge roller 206 on the conveyance path 3 in a direction away from the discharge inlet guide 313.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus such as a printer or a copying machine.

  In image forming apparatuses such as printers and copiers, steam is generated from the recording material warmed at the time of fixing, and the water adhering to the conveyance guide becomes water droplets. If the recording material is touched again, an image defect may occur. .

  In Patent Document 1, two sets of through rollers that are in contact with the recording material are disposed over the entire width direction orthogonal to the conveyance direction of the recording material as the discharge rollers after fixing. Thereby, it is possible to prevent image defects such as roller marks on the image and undulation of the recording material.

JP 2006-124104 A

  In Patent Document 1, it is not possible to solve the problem that vapor is generated from the recording material warmed at the time of fixing and the water adhering to the conveyance guide becomes water droplets and touches the recording material again.

  The present invention solves the above-described problems, and an object of the present invention is to provide an image forming apparatus that prevents condensation from adhering to a recording material after fixing.

  In order to achieve the above object, a typical configuration of an image forming apparatus according to the present invention includes a fixing unit that thermally fixes a developer on a recording material, and a first unit provided downstream of the fixing unit in the conveyance direction of the recording material. And a second through roller pair provided downstream of the first through roller pair in the conveying direction of the recording material. The fixing unit includes a heating unit and a recording material. A pressure unit facing the heating unit across the transport path, and further, the first and second through rollers on the opposite side of the heating unit across the transport path A conveyance guide provided between the pair, and an urging member that urges the recording material conveyed between the first and second through roller pairs of the conveyance path in a direction away from the conveyance guide. It is characterized by.

  According to the present invention, it is possible to prevent condensation from adhering to the recording material after fixing.

1 is an explanatory cross-sectional view illustrating a configuration of an image forming apparatus according to the present invention. FIG. 4 is an explanatory cross-sectional view illustrating a configuration of a conveyance path from a fixing unit to a discharge unit. FIG. 6 is an explanatory cross-sectional view illustrating a configuration of a conveyance guide provided in a conveyance path from a fixing unit to a discharge unit. It is front explanatory drawing which shows the structure of a through roller. It is a perspective explanatory view showing the configuration of the discharge inlet guide. It is a plane schematic diagram which shows the structure of a fixing air path and a discharge air path.

  An embodiment of an image forming apparatus according to the present invention will be specifically described with reference to the drawings.

<Image forming apparatus>
The configuration of the image forming apparatus 100 according to the present invention will be described with reference to FIG. FIG. 1 is an explanatory cross-sectional view showing a configuration of an image forming apparatus 100 according to the present invention. In the center of the image forming apparatus 100 shown in FIG. 1, image forming units 120Y, 120M, 120C, and 120K corresponding to the respective colors of yellow Y, magenta M, cyan C, and black K are provided. In some cases, the image forming units 120Y, 120M, 120C, and 120K are representatively described using the image forming unit 120. The same applies to other image forming process means.

  Each image forming unit 120 is provided with photosensitive drums 121Y, 121M, 121C, and 121K as image carriers that rotate in the direction of arrow A in FIG. The surface of each photosensitive drum 121 rotating in the clockwise direction in FIG. 1 is uniformly charged by each charging roller 4Y, 4M, 4C, 4K serving as charging means.

  Light corresponding to image information of each color is exposed on the surface of each uniformly charged photosensitive drum 121 by each scanner unit 122Y, 122M, 122C, 122K serving as an exposure unit. Thereby, an electrostatic latent image is formed on the surface of each photosensitive drum 121. Thereafter, toner (developer) is applied to the electrostatic latent image formed on the surface of each photosensitive drum 121 by each of the developing rollers 5Y, 5M, 5C, and 5K serving as a developer carrying member provided in the developing device serving as a developing unit. ) Is supplied. As a result, the electrostatic latent image formed on the surface of each photosensitive drum 121 is developed as a toner image.

  A transfer unit 6 is provided on the top of each photosensitive drum 121. The transfer unit 6 is provided with an intermediate transfer belt 130 that is rotatably stretched by a driving roller 131, a secondary transfer inner roller 104, and tension rollers 132 and 133 in the direction of arrow B in FIG.

  On the inner peripheral surface side of the intermediate transfer belt 130, primary transfer rollers 123Y, 123M, 123C, and 123K serving as primary transfer units are provided. When a primary transfer bias is applied to each primary transfer roller 123 from a primary transfer power source (not shown), each color toner image formed on the surface of each photosensitive drum 121 is sequentially superimposed on the outer peripheral surface of the intermediate transfer belt 130. Primary transcription. A secondary transfer outer roller 105 serving as a secondary transfer unit facing the secondary transfer inner roller 104 with an intermediate transfer belt 130 interposed therebetween is provided. A secondary transfer portion 103 is formed by the outer peripheral surface of the intermediate transfer belt 130 and the secondary transfer outer roller 105.

  On the other hand, a feeding cassette 101 containing a recording material S is provided at the bottom of the image forming apparatus 100 shown in FIG. The recording material S stacked on the intermediate plate 101 a provided in the feeding cassette 101 so as to be movable up and down is brought into contact with the pickup roller 1 when the intermediate plate 101 a is lifted. As the pickup roller 1 rotates counterclockwise in FIG. 1, the uppermost recording material S is fed out, and the uppermost recording material S is separated and fed one by one in cooperation with a separating means (not shown). The

  Thereafter, the paper is nipped and conveyed by the feeding roller 2 and guided to the conveyance path 3 formed by the conveyance guide 107. Then, the recording material S is nipped and conveyed by the conveyance roller 106 provided in the conveyance path 3, and the leading end portion of the recording material S is abutted against the nip portion of the registration roller 102 that is stopped, so that the skew of the recording material S is corrected. .

  Thereafter, the recording material S is nipped and conveyed by the registration roller 102 so that the image destination of the toner image carried on the outer peripheral surface of the intermediate transfer belt 130 reaches the secondary transfer unit 103, and the recording material S is transferred to the secondary transfer unit. It is conveyed to 103. When a secondary transfer bias is applied to a secondary transfer outer roller 105 from a secondary transfer power source (not shown), toner images carried on the outer peripheral surface of the intermediate transfer belt 130 are collectively recorded in the secondary transfer unit 103. Secondary transfer is performed on the material S.

  The toner remaining on the surface of each photosensitive drum 121 after the primary transfer is scraped and removed by cleaners 124Y, 124M, 124C, and 124K serving as cleaning means. On the other hand, the toner remaining on the outer peripheral surface of the intermediate transfer belt 130 after the secondary transfer is scraped off and removed by the cleaner 8 serving as a cleaning unit.

  The secondary transfer unit 103 includes a secondary transfer nip formed by a secondary transfer inner roller 104 and a secondary transfer outer roller 105 facing each other with the intermediate transfer belt 130 interposed therebetween. A predetermined pressing force and an electrostatic additional bias are applied to the recording material S conveyed to the secondary transfer unit 103. As a result, the unfixed toner image carried on the outer peripheral surface of the intermediate transfer belt 130 is attracted to the surface of the recording material S. The conveyance path 3 that conveys the recording material S includes a conveyance guide 107 that guides the recording material S while suppressing the behavior of the recording material S, a conveyance roller 106 that is disposed at an appropriate interval for holding the recording material S, and the like. Configured.

<Image forming operation>
An image forming operation of the toner image sent to the secondary transfer unit 103 in synchronization with the conveying operation of the recording material S from the feeding cassette 101 to the secondary transfer unit 103 will be described. Each color image forming unit 120 mainly includes a photosensitive drum 121, a scanner unit 122, a developing device (not shown) provided with the developing roller 5, etc., a primary transfer roller 123, a cleaner 124, and the like. .

  The surface of each photosensitive drum 121 rotating in the direction of arrow A in FIG. 1 is uniformly charged by the charging roller 4 serving as charging means. Each scanner unit 122 emits light based on an image information signal sent from an external device such as a personal computer (not shown), and the surface of each uniformly charged photosensitive drum 121 is irradiated with light corresponding to the image information. The Thereby, an electrostatic latent image is formed on the surface of each photosensitive drum 121.

  A developer is supplied to the electrostatic latent image formed on the surface of each photosensitive drum 121 by a developing roller 5 provided in a developing device (not shown) to be developed as a toner image. Thereafter, a predetermined pressing force and an electrostatic additional bias are applied by the primary transfer roller 123, and the toner image carried on the surface of each photosensitive drum 121 is transferred superimposed on the outer peripheral surface of the intermediate transfer belt 130. .

  Thereafter, the transfer residual toner slightly remaining on the surface of each photosensitive drum 121 is collected by each cleaner 124 to prepare for the next image formation again. The image forming unit 120 illustrated in FIG. 1 is an example in which four sets of yellow Y, magenta M, cyan C, and black K exist. In addition, the image forming unit 120 is not limited to four colors, and the order of colors can be changed as appropriate.

<Intermediate transfer belt>
Next, the configuration of the intermediate transfer belt 130 will be described. The intermediate transfer belt 130 is stretched by a driving roller 131, tension rollers 132 and 133, and a secondary transfer inner roller 104, and is driven to rotate in the direction of arrow B in FIG. The image forming process of each color, which is sequentially processed in parallel by the image forming units 120 of yellow Y, magenta M, cyan C, and black K, starts from the upstream toner image primarily transferred onto the outer peripheral surface of the intermediate transfer belt 130. This is done at the timing of sequential overlapping. As a result, a full-color toner image is finally formed on the outer peripheral surface of the intermediate transfer belt 130 and conveyed to the secondary transfer unit 103.

  The full color toner image is secondarily transferred onto the recording material S in the secondary transfer unit 103 by the conveying operation and the image forming operation of the recording material S. Thereafter, the recording material S carrying the unfixed toner image is conveyed to a fixing unit 150 serving as a fixing unit for thermally fixing the unfixed toner image (developer) to the recording material S. In the process in which the recording material S carrying the unfixed toner image is nipped and conveyed by the fixing roller 220 and the pressure roller 202 provided in the fixing unit 150 shown in FIG. Dissolved and fixed.

  The recording material S on which the toner image is fixed is discharged from the fixing unit 150, guided by the flapper 151, and discharged onto the discharge tray 160 by the discharge roller 208. Alternatively, the paper is further nipped and conveyed by the conveying roller 7, guided by the flapper 9, and discharged onto the discharge tray 161 by the discharge roller 10. Alternatively, when double-sided image formation is required, a route selection as to whether the paper is conveyed from the reverse path 162 to the double-sided conveyance path 163 is appropriately performed.

  The recording material S guided by the flapper 9 and sent to the reversing path 162 is nipped and conveyed by the reversing roller 11, and the reversing roller 11 is in a state where the trailing end of the recording material S is nipped by the reversing roller 11. Reverse rotation. As a result, the recording material S is guided to the double-sided conveyance path 163 and the front and back surfaces are reversed, and the recording material S joins the conveyance path 3 again and the image forming operation is similarly performed on the second surface side of the recording material S.

<Fixing part and discharging part>
Next, the configuration of the fixing unit and the discharge unit will be described with reference to FIG. FIG. 2 is an explanatory cross-sectional view illustrating the configuration of the conveyance path 3 from the fixing unit to the discharge unit.

<Fusing unit>
The fixing unit 150 shown in FIG. 2 includes a pressure roller 202, a fixing roller 220, a fixing discharge roller 204, and the like. The fixing discharge roller 204 serving as the first through roller pair is provided downstream of the fixing unit including the pressure roller 202 and the fixing roller 220 in the conveyance direction of the recording material S. The fixing discharge roller 204 has a one-way clutch or the like, and is configured such that the recording material S can be pulled out by a pre-discharge roller 206 provided downstream of the fixing discharge roller 204. The pre-discharge roller 206 is configured as a second pass roller pair provided downstream of the fixing discharge roller 204 (first pass roller pair) in the conveyance direction of the recording material S.

<Discharge unit>
A discharge unit 205 illustrated in FIG. 2 is an example of a transport unit that transports the recording material S discharged from the fixing unit 150. The discharge unit 205 is configured as a discharge unit that discharges the recording material S discharged from the fixing unit 150 to the outside of the apparatus. Note that the present invention can also be applied to a conveyance unit when the recording material S discharged from the fixing unit 150 is reversed and double-sided printing is performed.

  The discharge unit 205 is a pre-discharge roller 206 serving as a second through roller pair including a through roller 13 that contacts the recording material S over the entire width direction orthogonal to the conveyance direction of the recording material S used in the image forming apparatus 100. Have Further, the apparatus includes a discharge roller 208, a discharge sensor 211, a flapper 151, and the like.

  The flapper 151 switches whether the recording material S discharged from the fixing unit 150 is discharged to the discharge tray 160 or conveyed toward the discharge tray 161 or the reverse path 162. The recording material S that has passed through the secondary transfer unit 103 passes through the fixing unit 150 and the discharge unit 205, is guided to the discharge path 12 by the flapper 151 rotated to the posture position shown in FIG. It is conveyed and discharged onto the discharge tray 160.

<Transport guide>
Next, the configuration of the conveyance guide provided in the conveyance path 3 from the fixing unit to the discharge unit will be described with reference to FIG. FIG. 3 is an explanatory cross-sectional view illustrating a configuration of a conveyance guide provided in the conveyance path 3 from the fixing unit to the discharge unit. A recording material S carrying an unfixed toner image is sandwiched and conveyed by a fixing roller 220 constituting a heating unit provided in the fixing unit 150 shown in FIG. 3 and a pressure roller 202 constituting a pressure unit. At this time, the toner image is heated and melted, and is thermally fixed to the recording material S. The pressure roller 202 (pressure unit) is provided to face the fixing roller 220 (heating unit) with the conveyance path 3 through which the recording material S is conveyed.

  Here, in order to prevent the vapor generated from the recording material S such as paper from being heated by the fixing unit 150 from adhering to the discharge inlet guide 313, it is also possible to increase the air volume of the fixing air path 311 and the discharge air path 312. It is done. The discharge inlet guide 313 is on the side opposite to the fixing roller 220 side (heating unit side) across the conveyance path 3 and between the fixing discharge roller 204 and the pre-discharge roller 206 (between the first and second passing roller pairs). ) Is provided as a conveyance guide.

  On the other hand, the fixing discharge roller 204 and the pre-discharge roller 206 come into contact with the recording material S while the temperature of the recording material S after fixing is high. Then, the toner image immediately after the contact portion of the recording material S is rapidly cooled by the fixing discharge roller 204 and the pre-discharge roller 206 and thermally fixed on the recording material S may become gloss unevenness (gloss unevenness). Here, gloss unevenness (gloss unevenness) is an image defect that occurs on the surface of the recording material S due to a difference in cooling speed when the recording material S such as coated paper coated on the surface is used. In order to prevent such a phenomenon, the through roller 13 shown in FIG. 4 that contacts the recording material S over the entire width direction orthogonal to the conveyance direction of the recording material S is used for the fixing discharge roller 204 and the pre-discharge roller 206 after fixing. ing.

  If hot air heated by the fixing unit 150 is sent to the discharge unit 205, the cooling effect of the recording material S in the discharge unit 205 is reduced. Therefore, the fixing air path 311 provided in the fixing unit 150 and the discharge air path 312 provided in the discharge unit 205 are separated. Since the fixing discharge roller 204 and the pre-discharge roller 206 are constituted by the through roller 13, the air path formed by the conveying path 3 is divided. That is, in the conveyance path 3, there is a space where no wind enters between the fixing discharge roller 204 immediately after fixing and the pre-discharge roller 206 at the discharge inlet. Thereby, hot air heated by the fixing unit 150 is not sent to the discharge unit 205.

  Further, in the conveyance path 3, when air is sent from the discharge port side toward the space between the fixing discharge roller 204 including the through roller 13 immediately after fixing and the pre-discharge roller 206 including the through roller 13 at the discharge inlet. Consider. Also in this case, when the recording material S conveyed through the conveyance path 3 exists between the fixing discharge roller 204 and the pre-discharge roller 206, a path through which the wind can escape cannot be secured.

  Therefore, the wind does not reach the discharge inlet guide 313 (conveyance guide) that exists between the fixing discharge roller 204 and the pre-discharge roller 206. For this reason, the condensation of the discharge inlet guide 313 (conveyance guide) cannot be prevented. In order to secure a necessary air volume so that the discharge inlet guide 313 (conveyance guide) existing between the fixing discharge roller 204 and the pre-discharge roller 206 does not condense, the output of the blower fan (or suction fan) is It is necessary to use a high-priced one, which increases the size and cost of the device.

<Fixing air path and exhaust air path>
FIG. 6 is a schematic plan view showing the configuration of the fixing air passage 311 and the discharge air passage 312. As shown in FIG. 3, the water vapor emitted from the recording material S such as paper after fixing passes through the fixing air passage 311 serving as a first air passage provided in the fixing unit 150 on the rear side of the image forming apparatus 100 main body. It is sucked and collected by a suction fan 19 provided on (the upper side in FIG. 6).

  The opening 14 a of the duct 14 that forms the fixing air path 311 shown in FIG. 3 faces the opening 150 a provided downstream of the fixing roller 220 and the pressure roller 202 of the fixing unit 150 and upstream of the fixing discharge roller 204. Is provided. The air heated by the fixing unit 150 is sucked by the suction fan 19 through the opening 3a, the opening 150a, the opening 14a, and the duct 14 provided in the transport guide constituting the transport path 3, and is discharged outside the apparatus.

  The recording material S sandwiched and conveyed by the fixing discharge roller 204 and discharged from the fixing unit 150 is transferred to a pre-discharge roller 206 provided in the discharge unit 205. A discharge air passage 312 formed by the duct 20 shown in FIG. 6 is provided downstream of the pre-discharge roller 206.

  The discharge air passage 312 is provided in a second discharge unit 205 that constitutes a conveyance unit that conveys the recording material S discharged from the fixing unit 150 having a fixing unit constituted by the fixing roller 220 and the pressure roller 202. It is configured as a wind path. Air is blown through the discharge air passage 312 by the blower fan 21 provided on the front side (lower side in FIG. 6) of the image forming apparatus 100 main body. The air blown by the blower fan 21 enters the discharge path 12 through the opening 12a provided in the conveyance guide constituting the discharge path 12, and is discharged out of the apparatus through the discharge port 15. The fixing air passage 311 and the discharge air passage 312 (first and second air passages) may be air passages that perform either intake or exhaust.

  The recording material S sandwiched and conveyed by the pre-discharge roller 206 is guided to the discharge path 12 by the flapper 151 set at the rotation position shown in FIG. The discharge air passage 312 is communicated with the discharge passage 12, and the recording material S passing through the discharge passage 12 is cooled by air exhausted from the discharge air passage 312 through the discharge passage 12. Thereafter, the paper is nipped and conveyed by the discharge roller 208 and discharged onto the discharge tray 160.

<Threading roller>
Here, when the fixing discharge roller 204 and the pre-discharge roller 206 come into contact with the recording material S while the temperature of the recording material S after fixing is high, the contact portion is rapidly cooled by the fixing discharge roller 204 and the pre-discharge roller 206 and gloss unevenness ( (Gloss unevenness). In order to prevent such a phenomenon, the fixing discharge roller 204 and the pre-discharge roller 206 after fixing are applied to the recording material S over the entire width direction orthogonal to the conveyance direction of the recording material S used in the image forming apparatus 100. A threading roller 13 in contact is used.

  Next, the configuration of the through roller 13 will be described with reference to FIG. FIG. 4 is an explanatory front view showing the configuration of the threading roller 13. The through roller 13 shown in FIG. 4 includes a driving roller 401 and a driven roller 402. The roller surfaces of the driving roller 401 and the driven roller 402 are in contact with the recording material S over the entire width direction orthogonal to the conveying direction of the recording material S used in the image forming apparatus 100. In addition, among the driving roller 401 and the driven roller 402, only the roller disposed on the side where the toner image is fixed may be used as the passing roller 13.

  In this manner, the fixing air path 311 is provided upstream (fixing portion side) of the fixing discharge roller 204 including the through roller 13 immediately after fixing. In addition, a discharge air passage 312 is provided downstream (on the discharge passage 12 side) of the pre-discharge roller 206 including the passage roller 13 at the discharge inlet. The fixing air path 311 and the discharge air path 312 are divided by the fixing discharge roller 204 and the pre-discharge roller 206, and are formed as separate and independent air paths.

  The discharge air passage 312 is provided mainly for the purpose of cooling the recording material S after fixing. If hot air heated by the fixing unit 150 is sent to the discharge unit 205, the cooling effect of the recording material S in the discharge unit 205 is reduced. In order to avoid this, a fixing air passage 311 provided in the fixing unit 150 and a discharge air passage 312 provided in the discharge unit 205 are provided independently.

  Thus, the fixing discharge roller 204 (first passing roller pair) composed of two sets of the passing rollers 13 and the pre-discharge roller 206 (second passing roller pair) constitute a fixing air passage 311 (first air passage). And the discharge air passage 312 (second air passage). As a result, a space where no wind enters between the fixing discharge roller 204 and the pre-discharge roller 206 in the conveyance path 3 is formed. For this reason, the discharge inlet guide 313 is condensed.

  Also, consider the case where air is sent between the fixing discharge roller 204 and the pre-discharge roller 206 from the discharge port 15 side of the image forming apparatus 100 main body. In that case, when the recording material S conveyed through the conveyance path 3 exists between the fixing discharge roller 204 and the pre-discharge roller 206, a path through which the wind can escape cannot be secured. For this reason, an air volume falls and the effect with respect to dew condensation of the discharge inlet guide 313 is low.

<Exhaust entrance guide>
The configuration of the discharge inlet guide 313 will be described with reference to FIGS. 3 and 5. FIG. 5 is an explanatory perspective view showing the configuration of the discharge inlet guide 313. In this embodiment, the fixing air path 311 provided in the fixing unit 150 and the discharge air path 312 provided in the discharge unit 205 are divided by the fixing discharge roller 204 and the pre-discharge roller 206, respectively, which are constituted by the through rollers 13. Provided.

  As shown in FIG. 3, the conveyance guide is on the opposite side to the fixing roller 220 side (heating unit side) across the conveyance path 3 where the recording material S is conveyed, and downstream of the fixing roller 220 in the conveyance direction of the recording material S. A discharge inlet guide 313 is provided. The discharge inlet guide 313 (conveyance guide) guides the recording material S that is conveyed between the fixing discharge roller 204 and the pre-discharge roller 206 (between the first and second through rollers) in the conveyance path 3.

  A sensor serving as a detection unit that detects the recording material S conveyed between the fixing discharge roller 204 and the pre-discharge roller 206 in the conveyance path 3 (between the first and second through roller pairs) is provided in the discharge inlet guide 313. 18 is provided. The sensor 18 is provided with a sensor flag 309 serving as an urging member provided so as to be rotatable about a rotation shaft 309a.

  The sensor flag 309 is applied with a pressing force in the counterclockwise direction of FIG. 3 around a rotation shaft 309a by a torsion coil spring serving as a pressing means (not shown). And it is hold | maintained by the attitude | position which interrupts | blocks the conveyance path 3, as shown in FIG.

  When the recording material S that is nipped and conveyed by the fixing discharge roller 204 (first through roller pair) passes through the sensor flag 309, the recording material S rotates the sensor flag 309 against the pressing force of a torsion coil spring (not shown). It is pushed around the moving shaft 309a in the clockwise direction in FIG. On the other hand, the sensor flag 309 pushed in the clockwise direction in FIG. 3 is pushed back in the counterclockwise direction in FIG. 3 around the rotation shaft 309a by a torsion coil spring serving as a pressing means (not shown).

  As a result, the recording material S immediately after fixing that has passed through the fixing unit 150 is urged and moved in a direction away from the discharge inlet guide 313 (conveyance guide) by the reaction force received from the sensor flag 309. That is, the recording material S conveyed between the fixing discharge roller 204 and the pre-discharge roller 206 in the conveyance path 3 (between the first and second through rollers) is away from the discharge inlet guide 313 (conveyance guide). It is energized by and moves.

  The sensor 18 of the present embodiment is configured by a light shielding photosensor having a light emitting part and a light receiving part. The sensor flag 309 is provided with a light shielding portion (not shown), and the sensor 18 is provided with a light shielding portion that rotates integrally with the sensor flag 309 when the sensor flag 309 rotates about the rotation shaft 309a. The light path of the light receiving unit is blocked from the light emitting unit (not shown). Thereby, the passage of the recording material S can be detected by the sensor 18.

  The detection signal output from the sensor 18 is sent to the control unit 17 serving as a control unit, and the control unit 17 executes various controls of the image forming apparatus 100.

  The sensor flag 309 is provided on the side opposite to the fixing roller 220 provided with a fixing heater, with the recording material S conveyed in the conveyance path 3 interposed therebetween. The temperature on the fixing roller 220 side provided with the fixing heater is higher than that on the pressure roller 202 side. For this reason, a large amount of steam generated from the recording material S such as paper is generated mainly from the pressure roller 202 side having a low temperature opposite to the fixing roller 220 having a high temperature.

  That is, the sensor flag 309 (biasing member) discharges the recording material S conveyed between the fixing discharge roller 204 and the pre-discharge roller 206 in the conveyance path 3 (between the first and second through rollers). Biasing is performed in a direction away from the guide 313 (conveyance guide). As a result, the recording material S is transported along the transport path 3 in a state of being separated from the discharge inlet guide 313. Thereby, it is possible to suppress the recording material S from coming into contact with the dew condensation portion of the discharge inlet guide 313. As a result, image defects due to condensation can be prevented.

  Further, in the discharge inlet guide 313 shown in FIG. 5, an opening 502 is formed at a position facing the recording material S on the inner side surface 313a of the discharge inlet guide 313 (conveyance guide) for the purpose of reducing the transport surface on which condensation occurs. Further, a rib 503 protruding from the inner side surface 313a of the discharge inlet guide 313 is provided at a position facing the recording material S on the inner side surface 313a of the discharge inlet guide 313 (conveyance guide).

  Thereby, the surface area of the inner surface 313a of the discharge inlet guide 313 can be increased. Thereby, even when the inner surface 313a of the discharge inlet guide 313 is condensed, the condensation can be transferred from the opening 502 to the inside of the discharge inlet guide 313. The opening 502 formed on the inner side surface 313a of the discharge inlet guide 313 and the opening 14a of the duct 14 forming the fixing air passage 311 are separated by a partition wall (not shown).

  As shown in FIG. 3, the air path formed by the conveyance path 3 is a fixing discharge roller 204 including a through roller 13 provided in the fixing unit 150 and a pre-discharge including a through roller 13 provided in the discharge unit 205. It is divided by the roller 206. A large amount of steam generated from the recording material S such as paper heated by the fixing unit 150 is generated from the side opposite to the fixing roller 220 side where the fixing heater is provided. The temperature on the fixing roller 220 side where the fixing heater is provided is higher than that on the pressure roller 202 side. For this reason, a lot of steam having a high temperature is generated on the pressure roller 202 side having a low temperature.

  In the present embodiment, the recording material S conveyed on the conveyance path 3 is moved away from the discharge inlet guide 313 by the discharge inlet guide 313 between the fixing discharge roller 204 forming the conveyance path 3 and the pre-discharge roller 206. An energizing sensor flag 309 is provided.

  The recording material S that is nipped and conveyed by the fixing discharge roller 204 contacts the sensor flag 309 that is held in the posture shown in FIG. Then, the sensor flag 309 is pushed around the rotation shaft 309a in the clockwise direction in FIG. 3 against the pressure force of a torsion coil spring (not shown). At this time, the recording material S is separated from the inner surface 313 a of the discharge inlet guide 313 under the pressure of a torsion coil spring (not shown). As a result, water droplets condensed on the inner surface 313 a of the discharge inlet guide 313 do not adhere to the recording material S. As a result, it is possible to prevent condensation from adhering to the recording material S after the toner image is thermally fixed by the fixing unit 150.

S: Recording material 3 ... Conveying path 202 ... Pressure roller (fixing unit; pressure unit)
204... Fixing discharge roller (first through roller pair)
206: Pre-discharge roller (second through roller pair)
220... Fixing roller (fixing unit; heating unit)
309 ... Sensor flag (biasing member)
313: Discharge inlet guide (conveyance guide)

Claims (8)

A fixing unit for thermally fixing the developer to the recording material;
A first through roller pair provided downstream of the fixing unit in the recording material conveyance direction;
A second threading roller pair provided downstream of the first threading roller pair in the conveying direction of the recording material;
Have
The fixing unit is
A heating unit;
A pressure unit facing the heating unit across a conveyance path through which the recording material is conveyed;
Have
Furthermore,
A conveyance guide provided on the opposite side to the heating unit side across the conveyance path and between the first and second through roller pairs;
An urging member that urges the recording material conveyed between the first and second through roller pairs of the conveyance path in a direction away from the conveyance guide;
An image forming apparatus comprising: A first air path provided in the fixing unit;
A second air path provided in a transport unit that transports the recording material discharged from the fixing unit;
Have
The image forming apparatus according to claim 1, wherein the first air path and the second air path are divided by the first and second through roller pairs.   The image forming apparatus according to claim 1, wherein the urging member is a sensor flag provided in a sensor that detects a recording material conveyed along the conveyance path.   The sensor flag is rotatably provided on the conveyance guide, is held in a state where the conveyance path is blocked with a pressure applied by a pressure unit, and is nipped and conveyed by the first through roller pair. The recording material is urged to a side opposite to the conveyance guide by a reaction force received from the sensor flag when the recording material pushes the sensor flag against the pressure force. The image forming apparatus according to 3.   The image forming apparatus according to claim 1, wherein an opening is provided at a position facing the recording material of the conveyance guide.   The image forming apparatus according to claim 1, wherein a rib protruding from an inner surface of the conveyance guide is provided at a position facing the recording material of the conveyance guide.   The image forming apparatus according to claim 2, wherein the first and second air passages are air passages that perform either intake or exhaust.   The image forming apparatus according to claim 2, wherein the transport unit is a discharge unit that discharges the recording material discharged from the fixing unit to the outside of the apparatus.