JP2014186255A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the attitude of a recording medium from varying in entering a nip area between an image holding body and a transfer body throughout the entire length thereof.SOLUTION: An image forming apparatus includes: an image holding body holding an image; a transfer body which conveys a recording medium at a first nip area with the image holding body to transfer the image to a transfer surface of the recording medium; a first conveyance member which is arranged on the upstream side of the image holding body in a conveyance direction so as to be brought into contact with the recording medium on the side of the transfer surface; and a second conveyance member which conveys the recording medium held at a second nip area with the first conveyance member to the first nip area, and which is configured to discharge the recording medium from the second nip area in a direction shifted toward the transfer body with respect to an upstream end of the first nip area in the conveyance direction; and a guide member which is arranged in the discharge direction with respect to the second nip area and guides the recording medium discharged from the second nip area toward the image holding body.

Description

  The present invention relates to an image forming apparatus.

  Patent Document 1 discloses an image formation in which a sheet fed from a registration roller is guided to a transfer belt side along a guide member and is in close contact with the transfer belt at a position upstream of a transfer nip portion. An apparatus is disclosed.

Japanese Patent Laying-Open No. 2005-8391

  An object of the present invention is to suppress variations in the posture of entering the nip region between the image holding member and the transfer member over the entire length of the recording medium.

  According to a first aspect of the present invention, there is provided an image holding body that holds an image, a transfer body that conveys the recording medium in a first nip region between the image holding body and transfers the image onto a transfer surface of the recording medium. The recording medium is sandwiched by a second nip region between the first conveying member and the first conveying member disposed on the upstream side in the conveying direction with respect to the image holding member so as to contact the transfer surface side of the recording medium. A second transport member that is transported to the first nip region, and the discharge direction of the recording medium from the second nip region is set to be shifted toward the transfer body with respect to the upstream end in the transport direction of the first nip region. And a guide member that is provided in the discharge direction with respect to the second nip region and guides the recording medium discharged from the second nip region to the image holding member side.

  The invention according to claim 2 is provided with an opposing guide member disposed so as to oppose the guide member with the recording medium guided by the guide member interposed therebetween. The image forming apparatus according to claim 1, wherein the recording medium is conveyed so as to be guided only by the guide member.

  According to a third aspect of the present invention, the opposing guide member and the guide member include a first space for projecting the recording medium to a side opposite to the guide member at a downstream side portion of the guide member in the transport direction. 3. A second space that is larger than the first space and has a convex shape toward the guide member at the upstream side portion of the guide member in the transport direction is formed. This is an image forming apparatus.

  According to a fourth aspect of the present invention, there is provided an image holding body that holds an image, a transfer body that conveys the recording medium at a nip region between the image holding body and transfers the image onto a transfer surface of the recording medium, and The recording medium that is disposed upstream of the nip region in the transport direction and has the leading end reaching the nip region is convex toward the transfer surface at the downstream portion in the transport direction and toward the non-transfer surface at the upstream portion in the transport direction. An image forming apparatus comprising: a conveyance unit configured to convey the recording medium so as to be curved in a convex S shape.

  According to the configuration of the first aspect of the present invention, it is possible to suppress the variation in the posture of entering the nip region between the image holding member and the transfer member over the entire length of the recording medium, compared to the case without this configuration.

  According to the configuration of the second aspect of the present invention, it is possible to suppress the adhering matter adhering to the opposing guide member from adhering to the recording medium.

  According to the configuration of the third aspect of the present invention, as compared with the case where the second space is smaller than the first space, variation in the posture of entering the nip region between the image holding member and the transfer member is suppressed over the entire length of the recording medium. Is done.

  According to the configuration of the fourth aspect of the present invention, variation in the posture of entering the nip region between the image carrier and the transfer body is suppressed over the entire length of the recording medium as compared with the case where the recording medium is curved in a C shape. it can.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an exemplary embodiment. It is the figure which looked at the photosensitive drum concerning this embodiment, the transfer roll, and the registration roll pair in the axial direction. FIG. 6 is a diagram illustrating the behavior of a recording medium conveyed from a nip area formed by a registration roll pair to a nip area formed by a photosensitive drum and a transfer roll. FIG. 6 is a diagram illustrating the behavior of a recording medium conveyed from a nip area formed by a registration roll pair to a nip area formed by a photosensitive drum and a transfer roll. FIG. 6 is a diagram illustrating the behavior of a recording medium conveyed from a nip area formed by a registration roll pair to a nip area formed by a photosensitive drum and a transfer roll. FIG. 6 is a diagram illustrating the behavior of a recording medium conveyed from a nip area formed by a registration roll pair to a nip area formed by a photosensitive drum and a transfer roll. It is the figure which looked at the photoconductive drum which concerns on a comparative example, the transfer roll, and the registration roll pair in the axial direction.

  Below, an example of an embodiment concerning the present invention is described based on a drawing.

(Configuration of image forming apparatus 10)
First, the configuration of the image forming apparatus 10 will be described. FIG. 1 is a schematic diagram illustrating a configuration of the image forming apparatus 10.

  As shown in FIG. 1, the image forming apparatus 10 includes an apparatus main body 11 in which each component is housed. Inside the apparatus main body 11, a plurality of storage units 12 that store recording media P such as paper, an image forming unit 14 that forms an image on the recording medium P, and an image forming unit 14 are formed on the recording medium P. A fixing device 56 that fixes the image to the recording medium P, a transport unit 16 that transports the recording medium P from the storage unit 12 to the image forming unit 14, and a control unit 20 that controls the operation of each unit of the image forming apparatus 10. , Is provided. Further, a discharge unit 18 for discharging the recording medium P on which the image is fixed by the fixing device 56 is provided at the upper part of the apparatus main body 11.

  The image forming unit 14 includes a photosensitive drum 32 (an example of an image holding member) that holds an image. The photosensitive drum 32 rotates in one direction (for example, counterclockwise in FIG. 1). Around the photosensitive drum 32, a charging roll 23 as a charging device for charging the photosensitive drum 32 and the photosensitive drum 32 charged by the charging roll 23 are exposed in order from the upstream side in the rotation direction of the photosensitive drum 32. An exposure device 36 that forms an electrostatic latent image on the photosensitive drum 32, a developing device 80 that develops the electrostatic latent image formed on the photosensitive drum 32 by the exposure device 36 to form a black toner image, and A transfer roll 26 (an example of a transfer body) that transfers a black toner image formed on the photosensitive drum 32 by the developing device 80 to the recording medium P is provided.

  The exposure device 36 is configured to form an electrostatic latent image based on the image signal sent from the control unit 20. Examples of the image signal sent from the control unit 20 include an image signal acquired by the control unit 20 from an external device.

  A toner storage container 58 that stores toner is provided above the exposure device 36. A toner storage chamber 58 </ b> A that stores toner is formed inside the toner storage container 58. Between the toner storage container 58 and the developing device 80, a toner transport device 60 that transports toner from the toner storage chamber 58A of the toner storage container 58 toward the developing device 80 is provided.

  The transfer roll 26 is in contact with the photosensitive drum 32, and a nip region T (an example of a first nip region) that sandwiches the recording medium P between the transfer roll 26 and the photosensitive drum 32 is formed. . The transfer roll 26 transports the recording medium P between the photosensitive drum 32 and the upper side in the nip region T, and transfers the toner image formed on the photosensitive drum 32 to the recording medium P in the nip region T. It is like that. That is, the nip region T is a transfer position (transfer portion) at which the toner image formed on the photosensitive drum 32 is transferred to the recording medium P.

  The transport unit 16 includes a delivery roll 46 that sends out the recording medium P accommodated in each storage unit 12, a transport path 48 that transports the recording medium P sent out by the delivery roll 46, and a downstream direction in which each delivery roll 46 is transported. A pair of conveyance rolls 50 that convey the recording medium P provided on the side to the downstream side (a nip area TA described later) and the recording medium P conveyed by each pair of conveyance rolls 50 are nip areas T. A registration roll pair 70 (an example of a first conveyance member and a second conveyance member).

  Further, the transport unit 16 is arranged on the upstream side in the transport direction of the transfer roll 26 so as to face the non-transfer surface side of the recording medium P, and the transfer roll side guide 72 guides the leading end of the recording medium toward the nip region T. (An example of a guide member) and a photosensitive drum side guide 74 (an example of an opposite side guide member) disposed so as to face the transfer roll side guide 72 between the recording medium P guided by the transfer roll side guide 72. And.

  The fixing device 56 includes a heating roll 56A as a heating member and a pressure roll 56B as a pressure member. In the fixing device 56, the toner image transferred to the recording medium P by the transfer roll 26 is fixed to the recording medium P by heating by the heating roll 56A and pressing by the pressure roll 56B. A discharge roll 52 that discharges the recording medium P on which the toner image is fixed to the discharge unit 18 is provided above the fixing device 56 (downstream in the transport direction).

  Further, the reverse conveyance path 37 for reversing the recording medium P having the toner image fixed on one side and feeding it back to the nip region T is opposite to the photosensitive drum 32 with respect to the transfer roll 26 (right side in FIG. 1). ). When images are formed on both sides of the recording medium P, the recording medium P with the toner image fixed on one side is switched back by the discharge roll 52 and guided to the reverse conveyance path 37 and sent back to the nip region T. It is like that.

  Next, an image forming operation for forming an image on the recording medium P in the image forming apparatus 10 will be described.

  In the image forming apparatus 10, the recording medium P sent out from any of the storage units 12 by the sending roll 46 is sent to the nip region T by the transport roll pair 50 and the registration roll pair 70.

  On the other hand, in the image forming unit 14, the photosensitive drum 32 is charged by the charging roll 23, and then exposed by the exposure device 36, so that an electrostatic latent image is formed on the photosensitive drum 32. The electrostatic latent image is developed by the developing device 80, and a black toner image is formed on the photosensitive drum 32. This black toner image is transferred to the recording medium P in the nip region T by the transfer roll 26.

  The recording medium P onto which the toner image has been transferred is conveyed to the fixing device 56 and the toner image is fixed by the fixing device 56. When an image is formed only on one side of the recording medium P, the recording medium P is discharged to the discharge unit 18 by the discharge roll 52 after the toner image is fixed.

  When images are formed on both sides of the recording medium P, after the image is fixed on one side, the recording medium P is switched back by the discharge roll 52, reversed, and sent to the reverse conveyance path 37. Further, the recording medium is again fed into the nip region T from the reverse conveyance path 37, and an image is formed on the opposite surface where no image is recorded in the same manner as described above, and is discharged to the discharge unit 18 by the discharge roll 52. . As described above, a series of image forming operations are performed.

(Main part configuration)
As shown in FIG. 1, the registration roll pair 70 is disposed immediately before the nip area T by the photosensitive drum 32 and the transfer roll 26 (upstream in the conveyance direction with respect to the nip area T and closest to the nip area T). A nip area TA (an example of a second nip area) that sandwiches the recording medium P is formed between the registration roll pair 70.

  In addition, the registration roll pair 70 has a function of aligning the leading end of the recording medium P conveyed from the conveyance roll pair 50 in the width direction (the front-rear direction of the paper surface in FIG. 1) and conveying it to the nip region T. Specifically, the registration roll pair 70 stops driving in a predetermined period after the leading end of the recording medium P conveyed from the conveying roll pair 50 reaches the registration roll pair 70, so that the leading end of the recording medium P Are aligned in the width direction (the front-rear direction of the sheet of FIG. 1), and the recording medium P is transported by driving with the leading ends aligned.

  Further, the registration roll pair 70 is configured to transport the recording medium P to the nip region T at a predetermined timing so as to match the transfer position (transfer start position) and the leading end position of the recording medium P.

  Further, the conveyance speed of the recording medium P by the registration roll pair 70 is set to be higher than the conveyance speed of the recording medium P by the photosensitive drum 32 and the transfer roll 26.

  As shown in FIG. 2, the registration roll pair 70 has an axis center C3 of a registration roll 70A (an example of a first conveying member) disposed on the photosensitive drum 32 side (left side in FIG. 2). 2 on the right side) of the registration roll 70B (an example of the second conveying member) is disposed at a position higher than the axial center C4. That is, the line LB connecting the axis center C3 and the axis center C4 of the registration roll pair 70 has an angle with respect to the horizontal line H, and the tangent S2 passing through the nip region TA of the registration roll pair 70 is diagonally rightward in FIG. It extends upward.

  Thus, the registration roll pair 70 is configured such that the registration roll 70B sandwiches the recording medium P between the registration roll 70B from the diagonally lower side with respect to the registration roll 70A and conveys the recording roll P diagonally upward to the right in FIG.

  The photosensitive drum 32 and the transfer roll 26 are arranged so that the axial center C1 of the photosensitive drum 32 is positioned higher than the axial center C2 of the transfer roll 26. That is, a line LA connecting the axial center C1 of the photosensitive drum 32 and the axial center C2 of the transfer roll 26 has an angle with respect to the horizontal line H, and the nip region T between the photosensitive drum 32 and the transfer roll 26 is defined. A tangent line S1 passing therethrough extends obliquely upward to the right in FIG.

  As a result, the photosensitive drum 32 and the transfer roll 26 convey the recording medium P between the photosensitive drum 32 and the right side in FIG. ing.

  The tangent line S2 due to the registration roll pair 70 is shifted from the tangent line S1 due to the photosensitive drum 32 and the transfer roll 26 to the transfer roll 26 side (right side in FIG. 2). There is no crossing between them. That is, the discharge direction of the recording medium P from the nip area TA is set so as to be shifted toward the transfer roll 26 with respect to the upstream end in the transport direction of the nip area T. More specifically, the discharge direction of the recording medium P from the nip area TA is set so as to be shifted toward the transfer roll 26 with respect to the entry direction of the recording medium P into the nip area T. Note that the tangent line S1 and the tangent line S2 need only be inclined to the same side (for example, the right side in FIG. 2), and a relative angle between the angle of the line LA with respect to the horizontal line H and the angle of the line LB with respect to the horizontal line H. No difference is necessary. Therefore, the angle of the line LA with respect to the horizontal line H and the angle of the line LB with respect to the horizontal line H may be the same.

  The photosensitive drum side guide 74 is disposed on the upstream side in the conveyance direction with respect to the photosensitive drum 32 and on the downstream side in the conveyance direction with respect to the registration roll 70A so as to face the transfer surface side of the recording medium P. The photosensitive drum side guide 74 extends linearly between the registration roll 70A and the photosensitive drum 32 along the diagonally upper right side in FIG. Further, the photosensitive drum side guide 74 has a larger angle with respect to the horizontal line than the tangent lines S1 and S2 (has an angle close to the vertical direction).

  The photosensitive drum side guide 74 is closer to the developing device 80 than the transfer roll side guide 72, and as shown in FIG. 2, the cloud toner K leaked from the developing device 80 is exposed to the photosensitive drum side guide 74. May adhere to.

  The photosensitive drum side guide 74 is integrated with the apparatus main body 82 (housing) of the developing device 80, and the cloud toner K leaking from between the apparatus main body 82 of the developing device 80 and the photosensitive drum 32 is photosensitive. It is easy to accumulate in the downstream end portion (upper end portion) 74 </ b> A of the body drum side guide 74.

  The transfer roll side guide 72 includes an upstream guide portion 72A disposed on the registration roll pair 70 in the discharge direction of the recording medium P and across the tangent line S2 of the registration roll pair 70 (crossing the tangent line S2). A downstream guide portion 72B extending from the upper end portion of the upstream guide portion 72A to the photosensitive drum 32 side, and a protruding portion 72C protruding from the upper end portion of the downstream guide portion 72B to the transfer roll 26 side. . The downstream guide portion 72B and the protruding portion 72C form a corner portion 72D (front end guide of the recording medium).

  The upstream guide portion 72A and the downstream guide portion 72B of the transfer roll side guide 72 feed the leading end of the recording medium P discharged from the nip area TA by being conveyed by the registration roll pair 70 to the photosensitive drum 32 side (FIG. 2). To the left).

  The distance between the transfer roll side guide 72 and the photosensitive drum side guide 74 is wider at the upstream guide portion 72A (upstream side in the transport direction) than at the downstream guide portion 72B (downstream side in the transport direction). That is, the second space for the recording medium P curved in an S shape to be convex toward the transfer roll side guide 72 at the upstream side portion (upstream side guide portion 72A) of the transfer roll side guide 72 as will be described later. R2 is larger than the first space R1 for the recording medium P to protrude toward the photosensitive drum side guide 74 at the downstream portion (downstream guide portion 72B) of the transfer roll side guide 72. The second space R2 is wide on the transfer roll 26 side (the right side in FIG. 2).

  In the present embodiment, the nip area TA of the registration roll pair 70, the corner 72D, and the nip area T formed by the photosensitive drum 32 and the transfer roll 26 are arranged side by side from the photosensitive drum 32 side (left side in FIG. 2). Has been placed.

  Further, in the fixing device 56 of the present embodiment, the heating roll 56A and the pressure roll so that the recording medium P on which the toner image is fixed in the fixing device 56 is curved (curled) convexly toward the pressure roll 56B. 56B (nip portion between the heating roll 56A and the pressure roll 56B) is configured.

(Operation according to the embodiment)
Next, the operation according to the embodiment will be described.

  In the present embodiment, the recording medium P sent out from any of the accommodating portions 12 by the sending roll 46 is transported by the transport roll pair 50 to the nip area TA of the registration roll pair 70. The recording medium P conveyed to the nip area TA has its front end aligned by the registration roll pair 70 and is conveyed to the nip area T by the photosensitive drum 32 and the transfer roll 26 at a predetermined timing.

  As shown in FIG. 3, the recording medium P transported from the nip area TA to the nip area T by the registration roll pair 70 first hits the upstream guide portion 72 </ b> A of the transfer roll side guide 72 at the leading end passing through the registration roll pair 70. . Thereafter, the tip is guided by the upstream guide portion 72A and the downstream guide portion 72B and reaches the corner portion 72D as shown in FIG. Thereafter, the tip is guided to the photosensitive drum 32 by the corner portion 72D, hits the photosensitive drum 32, and reaches the nip region T along the outer periphery of the photosensitive drum 32 as shown in FIG. .

  When the leading end reaches the nip region T, the recording medium P is sandwiched between the photosensitive drum 32 and the transfer roll 26 with the leading end side being sandwiched by the nip region T between the photosensitive drum 32 and the transfer roll 26, as shown in FIG. And the rear end side is sandwiched between the nip areas TA of the registration roll pair 70 and is conveyed by the registration roll pair 70.

  Since the conveyance speed of the recording medium P of the registration roll pair 70 is set to be higher than the conveyance speed of the recording medium P by the photosensitive drum 32 and the transfer roll 26, the conveyance speed of the recording medium P in the nip region T is set. The amount of conveyance in the nip area TA increases. As a result, as shown in FIG. 6, a slack (loop) R is gradually formed on the recording medium P between the nip region T and the nip region TA.

  The slack (loop) R is convex toward the photosensitive drum side guide 74 side (left side in FIG. 2) at the downstream side portion (downstream guide portion 72B) of the transfer roll side guide 72 in the conveyance direction, and is upstream in the conveyance direction. It curves in an S shape that is convex toward the transfer roll side guide 72 side (right side in FIG. 2) at the (upstream side guide portion 72A).

  The recording medium P is convex to the transfer roll side guide 72 side (right side in FIG. 2) at the upstream side portion (upstream side guide portion 72A) of the transfer roll side guide 72. This is because the recording medium P is sent out.

  The recording medium P is convex toward the photosensitive drum side guide 74 side (left side in FIG. 2) at the downstream portion (downstream guide portion 72B) of the transfer roll side guide 72. The nip region T by the transfer roll 26 is shifted to the photosensitive drum 32 side (left side in FIG. 2) with respect to the tangent S2 by the registration roll pair 70, and recording from the diagonally lower left side to the photosensitive drum 32 and the transfer roll 26 is performed. This is because the medium P enters.

  Furthermore, in the present embodiment, the second space R2 for the recording medium P to be convex toward the transfer roll side guide 72 at the upstream side portion of the transfer roll side guide 72 is the recording medium P in the transfer roll side guide 72. Since the downstream portion is larger than the first space R1 for projecting toward the photosensitive drum side guide 74, the transfer roll side guide is larger than the portion projecting toward the photosensitive drum side guide 74. The amount of sag in the portion convex toward the 72 side increases.

  In addition, since the conveyance amount of the recording medium P in the nip area TA is larger than the conveyance amount of the recording medium P in the nip area T, a pressing force of the recording medium P to the nip area T is generated.

  On the other hand, in the comparative example (see FIG. 7) in which the slack (loop) R of the recording medium P is formed in a C shape between the nip region T and the nip region TA, the S-shaped slack (loop). Since the radius of curvature of the C-shaped sag (loop) R is larger than the radius of curvature of the recording medium P, when the leading end side of the recording medium P enters the nip region T (the state indicated by the solid line in FIG. 7 is small), recording is performed. When the rear end side of the medium P enters the nip region T (a state in which the slack (loop) indicated by a two-dot chain line in FIG. 7 is large), the posture (entry direction (entry angle)) of entering the nip region T is large. fluctuate.

  When the posture of the recording medium P entering the nip region T varies greatly, the pushing force of the recording medium P against the nip region T also varies, and the conveyance speed speed at the front end side and the rear end side of the recording medium P in the nip region T is also varied. Variations occur.

  In the comparative example, since the leading end of the recording medium P is guided by the photosensitive drum side guide 74, the recording medium P comes into contact with the cloud toner adhering to the photosensitive drum side guide 74. Dirty.

  In the comparative example, since the leading end of the recording medium P is guided by the photosensitive drum side guide 74 integrated with the apparatus main body 82 of the developing device 80, a thick paper or the like is used as the recording medium P. In such a case, the leading edge of the recording medium P may hit the photoreceptor drum side guide 74 strongly, and the toner image may be disturbed (impulse banding) due to the impact on the developing device 80.

  On the other hand, in the present embodiment, as described above, the slack (loop) R of the recording medium P is formed in an S shape between the nip region T and the nip region TA. Compared with the comparative example (FIG. 7) in which the sag (loop) R is formed, the radius of curvature of the sag (loop) is small, and the leading end side of the recording medium P enters the nip region T (a state in which the sag (loop) is small). When the rear end side of the recording medium P enters the nip region T (a state where the slack (loop) is large), the variation in the posture (entry direction (entrance angle)) of entering the nip region T is small. That is, in this embodiment, variation in the posture of entering the nip region T between the photosensitive drum 32 and the transfer roll 26 is suppressed over the entire length of the recording medium P.

  Further, in this embodiment, the portion that protrudes toward the photosensitive drum side guide 74 has a smaller amount of slack than the portion that protrudes toward the transfer roll side guide 72, and therefore, toward the photosensitive drum side guide 74. Compared to the case where the convex portion has a larger amount of sag than the convex portion toward the transfer roll side guide 72, variation in the posture of entering the nip region T between the photosensitive drum 32 and the transfer roll 26 is suppressed. Is done.

  As described above, since the variation in the posture of entering the nip region T is suppressed, the variation in the pushing force by which the recording medium P is pushed into the nip region T is also suppressed, and the leading end side of the recording medium P in the nip region T is suppressed. Speed fluctuation of the conveyance speed on the rear end side is suppressed. Thereby, fluctuations in the partial magnification of the transferred toner image are suppressed on the front end side and the rear end side of the recording medium P. Further, since the gap (GAP) between the transfer roll 26 and the recording medium P does not vary between the front end side and the rear end side of the recording medium P, discharge white spots due to the discharge generated in the gap between the transfer roll 26 and the recording medium P are detected. (Image defect) is also suppressed.

  Further, in this embodiment, since the leading end of the recording medium P is guided only by the transfer roll side guide 72, it does not contact the cloud toner K adhering to the photosensitive drum side guide 74, and contamination of the recording medium P is suppressed. Is done. Note that the intermediate portion of the recording medium P comes into contact with the photosensitive drum side guide 74 by being convex toward the photosensitive drum side guide 74, but any part of the recording medium P is also exposed to the photosensitive drum side guide 74. The downstream end of the transport direction to which the cloud toner K adheres is prevented from contacting.

  In this embodiment, since the leading end of the recording medium P is guided only by the transfer roll side guide 72, the leading end of the recording medium P is integrated with the apparatus main body 82 of the developing device 80. Therefore, the toner image disturbance (impulse banding) caused by the impact on the developing device 80 due to the leading edge of the recording medium P hitting the photosensitive drum side guide 74 is suppressed. Further, the cloud toner K attached to the photosensitive drum side guide 74 due to an impact caused by the leading edge of the recording medium P hitting the photosensitive drum side guide 74 is also suppressed.

  In the present embodiment, the recording medium P on which the toner image is fixed by the fixing device 56 is curved (curled) convexly toward the pressure roll 56B, so that an image is formed on one side in order to form an image on both sides. After that, the recording medium P transported again to the nip region T is transported from the nip region TA to the nip region T in a state of being convexly curved toward the photosensitive drum side guide 74 side. Makes good contact with the transfer roll side guide 72 and is guided by the transfer roll side guide 72.

  In the present embodiment, the nip area TA of the registration roll pair 70, the corner 72D, and the nip area T formed by the photosensitive drum 32 and the transfer roll 26 are aligned from the photosensitive drum 32 side (left side in FIG. 2). Therefore, the posture of the recording medium P when the registration roll pair 70 is conveyed from the nip area TA of the registration roll pair 70 to the corner portion 72D and guided by the corner portion 72D and enters the nip area T is stabilized.

(Modification)
In the above-described embodiment, the transfer roll 26 is in contact with the photosensitive drum 32 from the obliquely lower side. Alternatively, they may be contacted in the horizontal direction.

  In the above embodiment, similarly, the registration roll 70B is in contact with the registration roll 70A obliquely from below. However, the present invention is not limited to this, and the discharge direction of the recording medium P from the nip area TA is directed to the nip area T. As long as the recording medium P is displaced toward the transfer roll 26, the registration roll 70 </ b> B may contact the registration roll 70 </ b> A obliquely from the upper side or may contact the registration roll 70 </ b> A in the horizontal direction.

  In the above-described embodiment, the registration roll pair 70, the transfer roll 26, and the photosensitive drum 32 are configured to convey the recording medium P upward. However, the present invention is not limited thereto, and the registration roll pair 70, the transfer roll 26, and The direction in which the photosensitive drum 32 is transported may be, for example, the horizontal direction, and the transport direction of the transport member and the direction of gravity are irrelevant.

  In the above embodiment, the example using the photosensitive drum 32 has been described as an example of the image holding body. However, the present invention is not limited to this. For example, an image formed by a plurality of image forming units as an example of the image holding body. An intermediate transfer member (an intermediate transfer belt, an intermediate transfer drum, or the like) that transfers the toner image onto the recording medium P may be used.

  The present invention is not limited to the above-described embodiment, and various modifications, changes, and improvements can be made. For example, the modification examples described above may be appropriately combined.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 16 Conveyance part 26 Transfer roll (an example of a transfer body)
32 Photosensitive drum (an example of an image carrier)
70A registration roll (an example of a first conveying member)
70B registration roll (an example of a second conveying member)
72 Transfer roll side guide (an example of a guide member)
74 Photosensitive drum side guide (an example of a facing side guide member)
P Recording medium R1 First space R2 Second space T Nip area (an example of a first nip area)
TA nip area (example of second nip area)

Claims (4)

An image carrier for holding an image;
A transfer body that conveys the recording medium in a first nip region with the image holding body, and transfers the image to a transfer surface of the recording medium;
A first conveying member disposed on the upstream side in the conveying direction with respect to the image holding member so as to contact the transfer surface side of the recording medium;
The recording medium is sandwiched in a second nip area with the first conveying member and conveyed to the first nip area, and the discharge direction of the recording medium from the second nip area is the conveying direction of the first nip area. A second conveying member set to be shifted toward the transfer body with respect to the upstream end;
A guide member that is provided in the discharge direction with respect to the second nip region and guides the recording medium discharged from the second nip region toward the image carrier;
An image forming apparatus comprising: An opposing guide member disposed so as to face the guide member between the recording medium guided by the guide member,
The image forming apparatus according to claim 1, wherein the conveying member conveys the recording medium such that a leading end of the recording medium is guided only by the guide member. The opposing guide member and the guide member are
A first space for the recording medium to be convex toward the opposite side of the guide member at a downstream side portion in the transport direction of the guide member;
A second space that is larger than the first space, and the recording medium is convex toward the guide member at an upstream portion in the transport direction of the guide member;
The image forming apparatus according to claim 2. An image carrier for holding an image;
A transfer body that conveys the recording medium in a nip region with the image holding body, and transfers the image to a transfer surface of the recording medium;
The recording medium disposed upstream of the nip region in the transport direction and having the leading end reaching the nip region is convex toward the transfer surface at the downstream portion in the transport direction and the non-transfer surface side at the upstream portion in the transport direction. A conveying unit that conveys the recording medium so as to bend into an S-shape that is convex to a convex shape;
An image forming apparatus comprising:

Images