JP6270682B2 - Medium conveying apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a medium conveying apparatus and an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a printer, a copier, a facsimile machine, or a multifunction machine, for example, a printer, the surface of a photosensitive drum uniformly charged by a charging roller is exposed by an LED head, and an electrostatic latent image is formed. After the electrostatic latent image is developed by the developing unit and a toner image is formed on the photosensitive drum, the toner image is transferred to the paper and fixed to form an image on the paper. It has become.

  By the way, as a method for transferring the toner image to the paper, a first method for directly transferring the toner image on the photosensitive drum to the paper and a toner image on the photosensitive drum are transferred to the intermediate transfer belt in the primary transfer portion. There is a second method in which the toner image transferred to the intermediate transfer belt is transferred to a sheet in a secondary transfer portion.

  In a printer that transfers a toner image by the second method, a pair of rollers is disposed in the secondary transfer portion, and an intermediate transfer belt and a sheet are sandwiched between the rollers. However, in this type of printer, when the paper before reaching the secondary transfer portion touches the intermediate transfer belt, the toner image on the intermediate transfer belt is disturbed and the image quality is lowered.

  In view of this, a guide member is provided upstream of the secondary transfer portion in the paper transport direction, and the guide member prevents the paper from touching the intermediate transfer belt (see, for example, Patent Document 1). ).

JP 2012-168557 A

  However, in the conventional printer, when a highly rigid sheet such as a thick sheet is used, the rear end of the sheet that has passed through the guide member may jump up and hit the intermediate transfer belt. In this case, the toner image on the intermediate transfer belt is disturbed and the image quality is lowered. Also, abnormal noise occurs when the trailing edge of the paper hits the intermediate transfer belt.

  The present invention solves the problems of the conventional printer and prevents not only the image quality from deteriorating but also the occurrence of abnormal noise. The purpose is to provide.

  For this purpose, the medium conveying apparatus of the present invention includes a transfer roller pair that transfers the developer image on the transfer belt to the medium, and a medium guide unit that guides the medium to the transfer roller pair.

The medium guide unit includes a guide body and an elastic member disposed on the surface of the guide body that faces the medium.
The elastic member covers a surface of the guide body facing the medium, is formed on the downstream side of the fixed area fixed to the guide body and the fixed area in the medium transport direction, and is in contact with the guide body. A contact region that is detachably contacted, and a free end region that is formed on the downstream side of the contact region in the medium transport direction and includes a free end.
And the said guide main body is provided with the 1st guide part corresponding to the said fixed area | region, and the 2nd guide part corresponding to the said contact area | region.
The first guide part is inclined with respect to the second guide part.

  According to the present invention, the medium transport device includes the transfer roller pair that transfers the developer image on the transfer belt to the medium, and the medium guide unit that guides the medium to the transfer roller pair.

The medium guide unit includes a guide body and an elastic member disposed on the surface of the guide body that faces the medium.
The elastic member covers a surface of the guide body facing the medium, is formed on the downstream side of the fixed area fixed to the guide body and the fixed area in the medium transport direction, and is in contact with the guide body. A contact region that is detachably contacted, and a free end region that is formed on the downstream side of the contact region in the medium transport direction and includes a free end.
And the said guide main body is provided with the 1st guide part corresponding to the said fixed area | region, and the 2nd guide part corresponding to the said contact area | region.
The first guide part is inclined with respect to the second guide part.

  In this case, since the medium guide unit includes an elastic member having a free end on the downstream side in the conveyance direction of the medium on the surface facing the medium to be guided, the rear of the medium when passing through the medium guide unit. It is possible to attenuate the force of the edge jumping up toward the transfer belt.

  Therefore, since the developer image on the transfer belt is not disturbed, it is possible to prevent the image quality from deteriorating. In addition, since the force that the rear end of the medium jumps toward the transfer belt is attenuated, it is possible to prevent the generation of noise due to the rear end of the medium striking the transfer belt.

It is the schematic of the secondary transfer part in the 1st Embodiment of this invention. 1 is a conceptual diagram of a printer according to a first embodiment of the present invention. It is a side view of the upper guide in the 1st embodiment of the present invention. It is a rear view of the upper guide in the 1st embodiment of the present invention. It is a figure for demonstrating the amount of bending of a flexible area | region when not forming a slit in the front-end part of a flexible area | region in the 1st Embodiment of this invention. It is a figure for demonstrating the deflection amount of a flexible area | region at the time of forming a slit in the front-end part of the flexible area | region in the 1st Embodiment of this invention. It is a 1st figure which shows operation | movement of the medium guide part in the 1st Embodiment of this invention. It is a 2nd figure which shows operation | movement of the medium guide part in the 1st Embodiment of this invention. It is a 3rd figure which shows operation | movement of the medium guide part in the 1st Embodiment of this invention. It is a rear view of the upper guide in the 2nd Embodiment of this invention. It is a rear view of the upper guide in the 3rd Embodiment of this invention. It is a rear view of the upper side guide in the 4th Embodiment of this invention. It is a rear view of the upper side guide in the 5th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this case, a printer as an image forming apparatus will be described.

  FIG. 2 is a conceptual diagram of the printer according to the first embodiment of the present invention.

  In the figure, 10 is a printer, and Cs is a housing of the printer 10. A paper cassette 11 serving as a medium accommodating portion is disposed in the main body of the printer 10, that is, the lower part in the apparatus main body, and the paper P serving as a medium is accommodated in the paper cassette 11.

  The paper cassette 11 is swingably disposed about a support shaft sh1 as a swing center, and a paper stacking plate 102 as a medium stacking plate on which the paper P is stacked, and a paper P feeding side on the paper stacking plate 102. The lift-up lever 103 is provided so as to be swingable about the support shaft sh <b> 2, and the tip of the lift-up lever 103 is brought into contact with the back surface of the sheet stacking plate 102. Further, a motor 104 as a lift-up drive unit for lifting the paper stacking plate 102 is provided, and the support shaft sh2 and the motor 104 are connected.

  A paper feeding portion 20 as a paper feeding mechanism for feeding the paper P one by one is disposed on the paper feeding side of the paper cassette 11. The paper feeding unit 20 is provided with a pickup roller 21 disposed so as to be in pressure contact with the paper P, and a separation device for separating the paper P fed by the pickup roller 21 one by one. The separation device includes a feed roller 22 and a retard roller 23.

  A paper transport unit 30 is disposed on the downstream side of the paper feeding unit 20 in the transport direction of the paper P, and the first to third transports the paper P fed from the paper cassette 11 to the paper transport unit 30. Conveying roller pairs 31 to 33 are disposed as conveying members.

  Above the paper cassette 11, an image forming unit 40 for forming a toner image of each color as a developer image, and a toner image of each color formed in the image forming unit 40 as a transfer belt, and A primary transfer unit 44 that forms a color toner image by sequentially superimposing and transferring the image onto an intermediate transfer belt 43 as an intermediate transfer medium by a Coulomb force, and a color toner image formed on the intermediate transfer belt 43 from a sheet conveying unit 30. A secondary transfer unit 50 and the like for transferring to the fed paper P are disposed.

  The image forming unit 40 is arranged in series in the running direction (arrow A direction) of the intermediate transfer belt 43, and includes five image forming units 41 each including a photosensitive drum 42 as an image carrier, and each of the image forming units. An LED head (not shown) serving as an exposure device disposed opposite to the photosensitive drum 42 of the unit 41 is provided. Each image forming unit 41 includes a charging roller (not shown) serving as a charging device and a developer carrier. A developing roller or the like (not shown) is provided. In each image forming unit 41, the surface of the photosensitive drum 42 is uniformly charged by a charging roller, and is exposed by an LED head to form an electrostatic latent image as a latent image. The electrostatic latent image is developed by the device to form a toner image. Each image forming unit 41 is detachably attached to the apparatus main body.

  The primary transfer section 44 includes a driving roller 72 that is rotated to run the intermediate transfer belt 43 along each of the image forming units 41, a driven roller 73 that is rotated as the driving roller 72 rotates, and the A primary transfer roller 75 is provided as a first transfer member that is disposed along each image forming unit 41 and is opposed to each photosensitive drum 42 via an intermediate transfer belt 43. The secondary transfer unit 50 is disposed on the downstream side of the paper transport unit 30 in the transport direction of the paper P. The secondary transfer unit 50 is rotated along with the rotation of the drive roller 72, and the intermediate transfer belt 43 is moved together with the drive roller 72. A backup roller 51 to be stretched and a secondary transfer roller 52 as a second transfer member opposed to the backup roller 51 through an intermediate transfer belt 43 are provided. The backup roller 51 and the secondary transfer roller 52 constitute a transfer roller pair as a roller pair.

  Note that the first support roller 77 is disposed in the traveling direction of the intermediate transfer belt 43 in the traveling direction of the intermediate transfer belt 43, upstream of the backup roller 51 and inside the intermediate transfer belt 43, close to the backup roller 51. A second support roller 78 is disposed on the downstream side of the backup roller 51 and outside the intermediate transfer belt 43 in the vicinity of the backup roller 51, and the first support roller 77 is connected to the intermediate transfer belt 43. Is pushed outward, and the second support roller 78 pushes the intermediate transfer belt 43 inward.

  A fixing unit 80 is disposed on the downstream side of the secondary transfer unit 50 in the conveyance direction of the paper P. The fixing unit 80 includes a heating roller 81 as a first roller and a pressure roller 82 as a second roller, and a heating body ht is disposed in the heating roller 81 and the pressure roller 82. Then, the color toner image transferred to the paper P in the secondary transfer unit 50 is heated and pressurized in the fixing unit 80 and fixed on the paper P. As a result, a color image is formed on the paper P.

  A paper discharge unit 60 for discharging the paper P on which the color image is formed to the outside of the apparatus main body is disposed downstream of the fixing unit 80 in the conveyance direction of the paper P. The paper discharge unit 60 includes discharge roller pairs 61 to 64, and the paper P is conveyed by the discharge roller pairs 61 to 64, discharged from the apparatus main body through the discharge port 65, and stacked on the stacker 66.

  A reversing unit 70 is disposed between the paper discharge unit 60 and the paper transport unit 30 so that images can be formed on both sides of the paper P. The reversing unit 70 is discharged from the fixing unit 80. The sheet P is reversed and sent to the sheet transport unit 30. For this purpose, the reversing unit 70 has a two-pass printing route 71 for forming an image again on the first printing surface (front surface) and a two-sided printing route (not shown) for forming an image on the back surface of the first printing surface. Is provided.

  Next, details of the secondary transfer unit 50 will be described.

  FIG. 1 is a schematic view of a secondary transfer portion according to the first embodiment of the present invention, FIG. 3 is a side view of an upper guide according to the first embodiment of the present invention, and FIG. 4 is a first embodiment of the present invention. It is a rear view of the upper guide in the form.

  In the figure, 43 is an intermediate transfer belt, 77 is a first support roller, and 50 is a secondary transfer portion. The secondary transfer unit 50 includes a backup roller 51, a secondary transfer roller 52, and a medium guide unit 120, and a color on the intermediate transfer belt 43 is provided at a nip portion between the backup roller 51 and the secondary transfer roller 52. A portion where the toner image is transferred onto the paper P, that is, a transfer portion q1 is formed. The intermediate transfer belt 43, the secondary transfer unit 50, and the like constitute a medium transport device.

  The secondary transfer roller 52 is surrounded by a roller housing 115 except for an upper end portion that forms a transfer site q1. The roller housing 115 includes a lower housing 116 and an upper housing 117, and an upper end portion of the secondary transfer roller 52 forming the transfer portion q 1 is opposed to the backup roller 51 in an opening h 1 formed in the upper housing 117. It is done.

  Then, in order to guide the paper P sent from the paper transport unit 30 (FIG. 2) to the backup roller 51 and the secondary transfer roller 52 of the secondary transfer unit 50, and before the paper P reaches the transfer part q1. In order to prevent the intermediate transfer belt 43 from being touched, the medium guide portion 120 is disposed upstream of the transfer portion q1 in the transport direction of the paper P.

  The medium guide unit 120 conveys the sheet P in the direction of arrow B below the medium conveyance path Rt1 through which the sheet P is conveyed, and a lower guide 122 as a first medium guide for guiding the sheet P to the transfer site q1. And an upper guide 123 as a second medium guide that is disposed on the upper side of the medium transport path Rt1 so as to face the lower guide 122 and guides the paper P to the transfer portion q1. An inlet 131 for the paper P is formed on the side, and an outlet 132 for the paper P is formed on the transfer portion q1 side.

  The lower guide 122 is inclined from the inlet 131 and extends obliquely upward, and the inclined portion 135 as a first guide portion, and the front end of the inclined portion 135 (front end in the transport direction of the paper P). A horizontal portion 136 is provided as a second guide portion that extends horizontally from the outlet 132 to the outlet 132. The upper guide 123 is inclined obliquely downward from the inlet 131 and extends substantially parallel to the intermediate transfer belt 43, and an inclined portion 145 as a first guide portion, and the inclined portion The horizontal part 146 as a 2nd guide part extended horizontally from the front end of 145 to the exit 132 is provided. The upper guide 123 is disposed on the guide body 53 and the surface of the guide body 53 facing the paper P and the lower guide 122, that is, on the lower surface side so as to cover the lower surface. An elastic member 54 having a free end is provided on the downstream side in the transport direction. The guide body 53 is made of a metal material and is grounded.

  By the way, when a highly rigid sheet P such as a thick sheet is used, the rear end of the sheet P that has passed through the medium guide unit 120 may jump up and hit the intermediate transfer belt 43. In this case, the toner image on the intermediate transfer belt 43 is disturbed, and the image quality is deteriorated. Further, when the trailing edge of the paper P hits the intermediate transfer belt 43, an abnormal noise is generated.

  Therefore, in the present embodiment, the elastic member 54 of the upper guide 123 attenuates the force by which the trailing edge of the paper P jumps when it passes through the medium guide unit 120.

  The guide body 53 includes a holding portion P1 that holds the elastic member 54 in the inclined portion 145, and a restriction portion P2 that restricts deformation of the elastic member 54 in the horizontal portion 146. The elastic member 54 covers the lower surface of the guide main body 53 at the inclined portion 145, is fixed to the holding portion P1 by a fixing means, for example, a predetermined adhesive, and is held by the holding portion P1. ) AR1, an abutting area (which covers the lower surface of the guide main body 53 at the horizontal portion 146 and is abutted without being fixed to the restricting portion P2, and the deformation toward the intermediate transfer belt 43 side is restricted by the restricting portion P2. Non-adhesive region) AR2 and a free end region AR3 that protrudes forward from the front end of the guide body 53 toward the transfer portion q1 in the horizontal portion 146 and is not restricted in deformation in the present embodiment. .

  The restricting portion P2 is formed on the downstream side of the holding portion P1 in the conveyance direction of the paper P, and the contact area AR2 is formed on the downstream side of the fixed area AR1 in the conveyance direction of the paper P, and is a free end area. AR3 is formed downstream of the contact area AR2 in the transport direction of the paper P. Further, the contact area AR2 and the free end area AR3 constitute a flexible area F that is bent by receiving an external force from the paper P.

  In the transport direction of the paper P, the front end of the lower guide 122 is located downstream of the front end of the guide body 53 and upstream of the front end of the elastic member 54. The front end of the guide 122 is placed below the transfer site q1, and the front end of the upper guide 123 is placed at substantially the same height as the transfer site q1.

  In the present embodiment, the elastic member 54 is formed of an elastic material, for example, a resin film made of a polyester film. In order to increase the effect of attenuating the force that the trailing edge of the paper P jumps up when passing through the medium guiding unit 120, that is, to increase the attenuation effect by the elastic member 54, the amount of bending of the elastic member 54 is increased. For this reason, if the length of the free end area AR3 in the transport direction of the paper P is increased, the elastic member 54 itself may come into contact with the intermediate transfer belt 43.

  Therefore, in the present embodiment, as described above, the flexible region F that is bent by receiving an external force from the paper P is formed in the elastic member 54.

  Accordingly, the amount of bending of the elastic member 54 can be increased without increasing the length of the free end area AR3 in the transport direction of the paper P, and the damping effect by the elastic member 54 can be increased. In the contact area AR2, it is not necessary to apply an adhesive between the guide main body 53 and the elastic member 54. Therefore, the height of the medium conveyance path Rt1 between the horizontal portions 136 and 146 is set to the adhesive. Can be increased by the thickness of. As a result, it is possible to prevent the conveyance failure of the paper P.

  Further, in the free end of the elastic member 54, in the present embodiment, the front end of the flexible region F is provided at a plurality of locations in the direction perpendicular to the transport direction of the paper P, that is, in the width direction of the elastic member 54. The slits SL1 having a uniform groove width are formed in parallel with each other. As shown in FIG. 4, the elastic member 54 is shorter than the guide body 53 in the width direction, and the end portions Eg <b> 1 and Eg <b> 2 are placed closer to the center than both ends of the guide body 53. The slits SL1 are formed at an equal pitch in the width direction of the elastic member 54, leaving margins m1 and m2 on the center side from the ends Eg1 and Eg2. That is, the distance w1 between the slits SL1 is made constant.

  The slit SL1 is formed at least in the free end area AR3, and in this embodiment, the length δ1 of each slit SL1 in the transport direction of the paper P is slightly smaller than the length δ2 of the free end area AR3. Made longer.

  By the way, when the paper P is fed from the paper transport unit 30, the paper P may come into contact with the transport roller pairs 31 to 33 and the like, and may be charged accordingly. If the toner image contacts with the intermediate transfer belt 43 when guided by 120, the toner image on the intermediate transfer belt 43 is disturbed by static electricity, and the image quality deteriorates. In the present embodiment, as described above, the guide body 53 is formed of a metal material, and the length δ1 of each slit SL1 is slightly longer than the length δ2 of the free end region AR3. Even if the sheet P as it is guided is guided by the medium guiding unit 120, static electricity on the sheet P can be released to the guide body 53 by making the sheet P and the guide body 53 face each other through the slit SL1. . Therefore, the toner image on the intermediate transfer belt 43 is not disturbed by static electricity, and it is possible to prevent the image quality from deteriorating.

  The length δ1 of each slit SL1 can be made equal to the length of the flexible region F.

  In the flexible region F, when the paper P is transported, it is formed at a position closest to the edges Eg1 and Eg2 of the elastic member 54 from both edges of the paper P, that is, outside the paper P. Only the portion between the two slits is bent, and the portion outside the two slits is not bent.

  Therefore, the force by which the trailing edge of the paper P jumps up according to the width of the paper P can be appropriately attenuated.

  Next, the operation of the elastic member 54 when the slit SL1 is not formed at the front end portion of the flexible region F and when the slit SL1 is formed will be described. For convenience of explanation, it is assumed that the length δ1 of the slit SL1 is equal to the length of the flexible region F in the conveyance direction of the paper P.

  FIG. 5 is a diagram for explaining the amount of bending of the flexible region when a slit is not formed at the front end of the flexible region in the first embodiment of the present invention, and FIG. 6 is a diagram illustrating the first embodiment of the present invention. It is a figure for demonstrating the amount of bending of a flexible area | region at the time of forming a slit in the front-end part of the flexible area | region in a form.

  In the figure, 53 is a guide body, 54 is an elastic member, AR1 is a fixed region, AR2 is a contact region, AR3 is a free end region, and F is a flexible region.

  As shown in FIG. 5, when the slit SL1 is not formed in the flexible region F, the force that the trailing edge of the paper P conveyed in the direction of the arrow B jumps up is the entire Q1 in the width direction of the elastic member 54 (FIG. 5). Therefore, the amount of bending of the flexible region F becomes small. As a result, the elastic member 54 cannot sufficiently attenuate the force by which the trailing edge of the paper P jumps up.

  On the other hand, as shown in FIG. 6, when a plurality of slits SL <b> 1 are formed in the flexible region F, the force at which the trailing edge of the paper P conveyed in the direction of the arrow B jumps up. It is possible to add only to the parts Q2 and Q3 (hatched parts in the figure) between the two slits formed at the closest positions outside the edge, and not to the parts outside the two slits. The amount of bending of the bending region F increases. As a result, the elastic member 54 can sufficiently attenuate the force that the trailing edge of the paper P jumps up.

  It should be noted that the shorter the distance w1 between the slits SL1 and the greater the number of slits SL1, the more papers P having different widths can be handled. In the present embodiment, the distance w1 between the slits SL1 is set to 50 [mm] so that it can correspond to a standard size paper, for example, A4 size paper P, and 7 in the width direction of the elastic member 54. A slit SL1 is formed at a location.

  Next, the operation of the medium guide unit 120 configured as described above will be described.

  FIG. 7 is a first diagram showing the operation of the medium guiding portion in the first embodiment of the present invention, FIG. 8 is a second diagram showing the operation of the medium guiding portion in the first embodiment of the present invention, FIG. 9 is a third diagram showing the operation of the medium guiding unit in the first embodiment of the present invention.

  First, the paper P sent from the paper transport unit 30 (FIG. 2) is transported in the direction of the arrow B in the medium transport path Rt1, reaches the transfer site q1, and is sandwiched between the backup roller 51 and the secondary transfer roller 52. Then, as shown in FIG. 7, the rear end Pe is pushed by the upper guide 123 and bent in a direction away from the intermediate transfer belt 43.

  Subsequently, as shown in FIG. 8, when the trailing edge Pe of the sheet P passes through the medium guide unit 120, the trailing edge Pe of the sheet P tries to return to a direction approaching the intermediate transfer belt 43 due to the elasticity of the sheet P itself. However, when the flexible region F of the elastic member 54 is bent, it is possible to prevent the elastic member 54 from returning in the direction approaching the intermediate transfer belt 43.

  Therefore, as shown in FIG. 9, the rear end Pe of the paper P is brought into contact with the intermediate transfer belt 43 in a state where the force of jumping up toward the intermediate transfer belt 43 is attenuated.

  Thus, in the present embodiment, the upper guide 123 has an elastic member 54 that has a free end on the lower surface side facing the paper P guided on the medium transport path Rt1 and on the downstream side in the transport direction of the paper P. Therefore, the elastic member 54 can attenuate the force that the trailing edge Pe of the paper P jumps toward the intermediate transfer belt 43 when it passes through the paper guide 120.

  Therefore, the toner image on the intermediate transfer belt 43 is not disturbed, and it is possible to prevent the image quality from deteriorating. In addition, the force by which the rear end Pe of the paper P jumps toward the intermediate transfer belt 43 is attenuated, so that it is possible to prevent the generation of noise due to the rear end Pe of the paper P hitting the intermediate transfer belt 43. .

  Next, a second embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st Embodiment, the same code | symbol is provided and the effect of the same embodiment is used about the effect of the invention by having the same structure.

  FIG. 10 is a rear view of the upper guide according to the second embodiment of the present invention.

  In this case, in the width direction of the elastic member 54, the rigidity of the elastic member 54 is made different, and the distances wi (i = 11, 12,...) Between the slits SL2 are made different from each other.

  Thereby, in the width direction of the elastic member 54, the amount of bending of the portion Qi (i = 11, 12,...) Between the slits SL2 is made different, so the amount of bending of the portion where the distance wi between the slits SL2 is short. , And the amount of bending at the portion where the distance wi between the slits SL2 is long can be reduced.

  Accordingly, the timing at which the rear end Pe of the sheet P as the medium abuts on the intermediate transfer belt 43 as the transfer belt and as the intermediate transfer medium is made different for each portion Qi, and between the slits SL2. The timing at which the rear end Pe of the paper P contacts the intermediate transfer belt 43 in the portion where the distance wi is short is delayed, and the rear end Pe of the paper P contacts the intermediate transfer belt 43 in the portion where the distance wi between the slits SL2 is long. Since the timing is advanced, the elastic member 54 can attenuate the rear edge Pe of the paper P in the width direction of the elastic member 54 by making it different.

  As a result, the toner image on the intermediate transfer belt 43 is not disturbed, and it is possible to prevent the image quality from deteriorating. In addition, the force by which the rear end Pe of the paper P jumps toward the intermediate transfer belt 43 is attenuated, so that it is possible to prevent the generation of noise due to the rear end Pe of the paper P hitting the intermediate transfer belt 43. .

  Next, a third embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st, 2nd embodiment, the same code | symbol is provided and the effect of the same embodiment is used about the effect of the invention by having the same structure.

  FIG. 11 is a rear view of the upper guide according to the third embodiment of the present invention.

  In this case, in the width direction of the elastic member 54, the distances wj (j = 21, 22,...) Between the slits SL3 are made different from each other and symmetrical, and are longer toward the center side of the elastic member 54. Both ends are shortened.

  Thereby, in the width direction of the elastic member 54, each bending amount of the part Qj (j = 21, 22,...) Between the slits SL3 is made different, so that the distance wj between the slits SL3 is a short part on both ends. The deflection amount of the central portion where the distance wj between the slits SL3 is long can be reduced.

  Accordingly, the timing at which the rear end Pe of the sheet P as a medium abuts on the intermediate transfer belt 43 as the transfer belt and the intermediate transfer medium is made different for each portion Qj, and the distance between the slits SL3. The timing at which the rear end Pe of the paper P abuts against the intermediate transfer belt 43 is delayed at the both end portions where wj is short, and the rear end Pe of the paper P is intermediate transferred at the central portion where the distance wj between the slits SL3 is long. Since the timing of contact with the belt 43 is advanced, the elastic member 54 can attenuate the force by which the trailing edge of the paper P jumps up in the width direction of the elastic member 54.

  As a result, the toner image on the intermediate transfer belt 43 is not disturbed, and it is possible to prevent the image quality from deteriorating. In addition, the force by which the rear end Pe of the paper P jumps toward the intermediate transfer belt 43 is attenuated, so that it is possible to prevent the generation of noise due to the rear end Pe of the paper P hitting the intermediate transfer belt 43. .

  Further, in the width direction of the elastic member 54, the force that the trailing edge Pe of the paper P jumps is symmetric and attenuated, so that the timing at which the trailing edge Pe of the paper P contacts the intermediate transfer belt 43 is symmetrical. Can be different. As a result, it is possible to prevent the sheet P from being skewed.

  Next, a fourth embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st-3rd embodiment, the same code | symbol is provided and the effect of the same embodiment is used about the effect of the invention by having the same structure.

  FIG. 12 is a rear view of the upper guide according to the fourth embodiment of the present invention.

  In this case, the rigidity of the elastic member 54 in the width direction is varied, and the length of the elastic member 54 in the transport direction of the paper P as a medium is varied as shown in the figure. That is, the flexible region distance Lf, which is the distance from the front end to the rear end of the flexible region F, is made different, the flexible region distance LEg1 on the one end Eg1 side of the elastic member 54 is the longest, and the elastic member 54 The flexible region distance LEg2 on the other end Eg2 side is minimized.

  As a result, the amount of bending of each part in the width direction of the elastic member 54 is made different, so that the amount of bending on the one end Eg1 side of the elastic member 54 is increased and the amount of bending on the other end Eg2 side of the elastic member 54 is increased. Can be reduced.

  Therefore, the timing at which the rear end Pe of the paper P abuts on the intermediate transfer belt 43 as the transfer belt and the intermediate transfer medium is made different, and the rear end of the paper P on the one end Eg1 side of the elastic member 54 is changed. The timing at which Pe contacts the intermediate transfer belt 43 is delayed, and the timing at which the rear end Pe of the sheet P contacts the intermediate transfer belt 43 on the other end Eg2 side of the elastic member 54 is advanced. In the width direction, the force by which the rear end Pe of the paper P jumps up can be attenuated.

  As a result, the toner image on the intermediate transfer belt 43 is not disturbed, and it is possible to prevent the image quality from deteriorating. In addition, the force by which the rear end Pe of the paper P jumps toward the intermediate transfer belt 43 is attenuated, so that it is possible to prevent the generation of noise due to the rear end Pe of the paper P hitting the intermediate transfer belt 43. .

  Next, a fifth embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st-4th embodiment, the same code | symbol is provided and the effect of the embodiment is used about the effect of the invention by having the same structure.

  FIG. 13 is a rear view of the upper guide according to the fifth embodiment of the present invention.

  In this case, in the width direction of the elastic member 54, the length of the elastic member 54 in the transport direction of the paper P as a medium is varied. That is, as shown in the figure, the flexible region distance Lf is varied in the width direction of the elastic member 54, the flexible region distance LEc is longer toward the center of the elastic member 54, and both ends Eg1, Eg2 of the elastic member 54 are longer. The flexible region distance LEg is shortened toward the side.

  As a result, the amount of bending of each portion in the width direction of the elastic member 54 can be made different, so that the amount of bending on the center side of the elastic member 54 can be increased, and the amount of bending on the ends Eg1, Eg2 side of the elastic member 54 can be reduced. it can.

  Therefore, the timing at which the rear end Pe of the paper P abuts on the intermediate transfer belt 43 as the transfer belt and the intermediate transfer medium is varied, and the rear end Pe of the paper P is intermediate transferred on the center side of the elastic member 54. The timing of contact with the belt 43 is delayed, and the timing at which the rear end Pe of the sheet P contacts the intermediate transfer belt 43 on both ends Eg1, Eg2 side of the elastic member 54 is advanced. The force by which the rear end Pe of P jumps up can be attenuated.

  As a result, the toner image on the intermediate transfer belt 43 is not disturbed, and it is possible to prevent the image quality from deteriorating. In addition, the force by which the rear end Pe of the paper P jumps toward the intermediate transfer belt 43 is attenuated, so that it is possible to prevent the generation of noise due to the rear end Pe of the paper P hitting the intermediate transfer belt 43. .

  Further, in the width direction of the elastic member 54, the force that the trailing edge Pe of the paper P jumps is symmetric and attenuated, so that the timing at which the trailing edge Pe of the paper P contacts the intermediate transfer belt 43 is symmetrical. Can be different. Therefore, it is possible to prevent the sheet P from being skewed.

  In each of the above embodiments, the printer 10 as an image forming apparatus has been described. However, the present invention can be applied to a multifunction printer, a copying machine, a facsimile machine, a multifunction machine, and the like.

  The present invention is not limited to the above embodiments, and various modifications can be made based on the gist of the present invention, and they are not excluded from the scope of the present invention.

43 Intermediate transfer belt 50 Secondary transfer portion 51 Backup roller 52 Secondary transfer roller 54 Elastic member 120 Medium guide portion P Paper

Claims (13)

(A) a transfer roller pair for transferring the developer image on the transfer belt to a medium;
(B) having a medium guide part for guiding the medium to the transfer roller pair;
(C) The medium guide unit includes a guide body and an elastic member disposed on a surface of the guide body facing the medium .
(D) The elastic member covers a surface of the guide body facing the medium, and is formed on the downstream side of the fixed area fixed to the guide body and the fixed area in the medium transport direction. A contact region that is slidably contacted, and a free end region that is formed on the downstream side of the contact region in the conveyance direction of the medium and includes a free end;
(E) The guide body includes a first guide portion corresponding to the fixed region, and a second guide portion corresponding to the contact region,
(F) The medium conveying apparatus, wherein the first guide portion is inclined with respect to the second guide portion . Before SL free end region, the medium conveying device according to claim 1 which is formed to protrude forward from the front end of the guide body in the conveying direction of the medium. Wherein the free end of the elastic member, the medium conveying device according to claim 1 or 2 comprising a slit formed at a plurality of positions in the width direction of the elastic member. Wherein each slit, the medium conveying device according to claim 3 which is formed parallel to each other toward the upstream side in the transport direction of the medium from the free end of the elastic member. Wherein each slit, the medium conveying device according to claim 3 or 4 is formed on at least the free end region. Medium transport device according to any one of claims 3-5 where the distance between the slits is constant in the width direction of the elastic member. Medium transport device according to any one of the resilient the ~ claim 3 where the distance is varied between each slit in the width direction of the member 5. The medium conveying apparatus according to claim 7 , wherein a distance between the slits in the elastic member is longer toward a center side of the elastic member and shorter toward both ends. The elastic members medium conveying device according to claim 1 or 2 rigidity of the elastic member is varied in the width direction of the. The medium transport apparatus according to claim 9 , wherein the length of the elastic member in the medium transport direction is varied in the width direction of the elastic member. The medium conveyance device according to claim 10 , wherein a length of the elastic member in the medium conveyance direction is longer toward a center side of the elastic member and shorter toward both ends. The elastic member is medium conveying device according to any one of claims 1 to 11 comprising a polyester film. An image forming apparatus on which the medium conveyance device according to any one of claims 1 to 12 is mounted.

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