JP5644144B2 - Medium conveying apparatus and image forming apparatus - Google Patents

Description

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

  As an image forming apparatus that forms an image on a sheet-like recording medium, an image forming apparatus that includes a pair of rolls that convey a sheet with a sheet interposed therebetween is known (for example, see Patent Document 1).

JP 2007-86480 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a medium conveying apparatus and an image forming apparatus in which the disturbance of an image formed on a medium is suppressed while reducing power for conveying a recording medium.

A medium conveying apparatus according to claim 1 is provided.
A pair of rotating members that rotate in a state where the peripheral surfaces are in contact with each other, the first pair of rotating rotating members that convey by sandwiching a sheet-like recording medium having an image formed on the surface;
The recording medium is guided and slid to guide the recording medium along the curved path to the first transport rotating member pair. The recording medium has a path on which the image is formed on both sides. A guide member disposed both inside and outside the path, which is guided toward the inside of the path;
The recording medium is a second transport rotating member pair formed of a rotating member that rotates in a state where the peripheral surfaces are in contact with each other. The recording medium is transported by sandwiching the recording medium and sent to the path. A second conveyance rotation member pair whose rotation is finished before the recording medium is separated from the second conveyance rotation member after reaching the conveyance rotation member pair.
A rotating body that is arranged alongside the guide member and rotates when the recording medium comes into contact with a peripheral surface is provided inside the path.

The medium transporting apparatus according to claim 2 is such as to prevent a recording medium having a basis weight of 106 g / m ² or more from coming into contact with the inner guide member provided inside the path among the guide members, and the basis weight. The rotating body protrudes toward the outside of the path from the inner guide member to such an extent that a recording medium having an amount of 81 g / m ² or less comes into contact with the inner guide member.

  According to a third aspect of the present invention, there is provided a medium conveying apparatus according to a first aspect of the present invention, wherein an upstream side in a conveying direction for conveying the recording medium is disposed in a clamping region where the rotating members constituting the first conveying rotating member pair come into contact with each other to sandwich the recording medium. A conveyance direction in which the recording medium is conveyed in a clamping area where the first straight line connecting the end and the downstream end and the rotation member forming the second conveyance rotation member pair come into contact with each other to sandwich the recording medium The first straight line and the second straight line on a circle in contact with the second straight line connecting the upstream end and the downstream end, and the first straight line, the second straight line, and the circumferential surface of the rotating body. It is characterized in that it is provided at a position avoiding a curve composed of an arc connecting the two.

  According to a fourth aspect of the present invention, there is provided the medium transporting apparatus according to the fourth aspect, wherein the guide member disposed inside the path along with the rotating body is in contact with the rotating members forming the first transport rotating member pair to sandwich the recording medium. The first straight line connecting the upstream end and the downstream end in the transport direction in which the recording medium is transported in the sandwiching region to be attached, and the rotating member forming the first transport rotating member pair come into contact with each other. A second straight line that connects an upstream end and a downstream end in the transport direction in which the recording medium is transported, a first straight line, the second straight line, and the rotating body in a sandwiching region that sandwiches the recording medium. A guide member disposed on the inner side of a curve composed of the first straight line and a circular arc connecting the second straight line on a circle in contact with the circumferential surface of the first conveying rotation member pair. The first deployed near the inside of the route A third straight line in contact with both the peripheral surface of the member and the peripheral surface of the rotating body, and the peripheral surface of the second rotating member disposed closer to the inside of the path of the second transport rotating member pair and the rotation It is characterized in that it is arranged closer to the outside of this path than at least one of the fourth straight lines in contact with both of the peripheral surface of the body.

An image forming apparatus according to claim 5
An image forming unit that forms an image on the surface of a sheet-like recording medium;
A pair of rotating members that rotate in a state where the peripheral surfaces are in contact with each other, and a first conveying rotating member pair that conveys by sandwiching a recording medium on which an image is formed by the image forming unit;
The recording medium is guided and slid to guide the recording medium along the curved path to the first transport rotating member pair. The recording medium has a path on which the image is formed on both sides. A guide member disposed both inside and outside the path, which is guided toward the inside of the path;
The recording medium is a second transport rotating member pair formed of a rotating member that rotates in a state where the peripheral surfaces are in contact with each other. The recording medium is transported by sandwiching the recording medium and sent to the path. A second conveyance rotation member pair whose rotation is finished before the recording medium is separated from the second conveyance rotation member after reaching the conveyance rotation member pair.
A rotating body that is arranged alongside the guide member and rotates when the recording medium comes into contact with a peripheral surface is provided inside the path.

  The medium conveying apparatus according to the first aspect can suppress the disturbance of the image formed on the recording medium while reducing the power for conveying the recording medium.

  The medium conveying apparatus according to the second aspect can suppress image disturbance due to sliding of the recording medium while stabilizing the guidance of the recording medium.

  According to the third and fourth aspects of the present invention, the medium conveyance device can also stabilize the guidance of the recording medium and suppress image disturbance due to the sliding of the recording medium.

  The image forming apparatus according to the fifth aspect can suppress disturbance of an image formed on the recording medium while reducing power for conveying the recording medium.

1 is a schematic cross-sectional view showing a copying machine which is an embodiment of an image forming apparatus of the present invention. FIG. 2 is an enlarged configuration diagram illustrating a front / back reversing path portion of the paper transport unit illustrated in FIG. 1. It is a block diagram which expands and shows the curved path | route among the front-back inversion paths shown in FIG. It is a perspective view which shows the member arrange | positioned around the curved path | route shown in FIG. It is a figure explaining the positional relationship of the member of the curved path periphery shown in FIG. It is a 1st figure explaining a mode that a cardboard is conveyed along the curved path | route shown in FIG. FIG. 4 is a second diagram illustrating a state in which thick paper is conveyed along the curved path illustrated in FIG. 3. FIG. 4 is a third diagram illustrating a state in which thick paper is conveyed along the curved path illustrated in FIG. 3. FIG. 6 is a fourth diagram illustrating a state in which thick paper is conveyed along the curved path illustrated in FIG. 3. It is a figure explaining a mode that a cardboard is conveyed through the curved path of the comparative example which does not have a rotary body. It is a 1st figure explaining a mode that thin paper is conveyed through the curved path | route shown in FIG. FIG. 4 is a second diagram illustrating how thin paper is conveyed along the curved path illustrated in FIG. 3. FIG. 4 is a third diagram for explaining how thin paper is conveyed along the curved path shown in FIG. 3. FIG. 6 is a fourth diagram illustrating a state in which thin paper is conveyed along the curved path illustrated in FIG. 3. FIG. 10 is a fifth diagram illustrating a state in which thin paper is conveyed along the curved path illustrated in FIG. 3.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic sectional view showing a copying machine as an embodiment of the image forming apparatus of the present invention.

  A copying machine 1 shown in FIG. 1 controls an image reading unit 10 that reads an image from a document, an image forming unit 20 that forms an image on a sheet, a sheet conveying unit 30 that conveys a sheet, and each unit of the copying machine 1. Part 40. The copier 1 also includes paper storage units 50A, 50B, and 50C that store paper, and toner containers 60A, 60B, 60C, 60D, 60E, and 60F that store toner of six colors used for image formation. Is provided. The paper transport unit 30 takes out the paper from the paper storage units 50 </ b> A, 50 </ b> B, and 50 </ b> C and transports the transport route R <b> 1 through the image forming unit 20. The image reading unit 10 reads an image from a document and generates image data. The image forming unit 20 forms an image on the sheet conveyed by the sheet conveying unit 30 based on the image data generated by the image reading unit 10.

  The image forming unit 20 has an electrostatic latent image or toner image formed on the surface thereof, a photosensitive drum 21 rotating in the direction of arrow A in the figure, a charger 22 for charging the photosensitive drum 21, and image data input. Then, an exposure unit 23 that irradiates the photosensitive drum 21 with exposure light modulated based on the image data to form an electrostatic latent image, and forms a toner image by applying toner to the electrostatic latent image. Primary transfer of the toner image formed on the photosensitive drum 21 to the intermediate transfer belt 25, which is in contact with the developing unit 24, and in contact with the photosensitive drum 21 and circulates in the direction of arrow B in FIG. From the paper storage units 50A, 50B, and 50C, the secondary transfer roll 26, the photosensitive drum cleaner 27 that cleans the photosensitive drum 21 after the primary transfer, and the toner image that has been primarily transferred onto the intermediate transfer belt 25, for A secondary transfer device 28 for secondary transfer from the transport unit 30 to the paper transported by the paper transport unit 30 and a fixing device 29 for fixing the toner image transferred onto the paper by heating and pressurizing it. Is provided. The copier 1 also includes a warp correction device 70 that corrects the warp of the paper on which the toner image is fixed, and a stacking tray 80 on which the paper on which the toner image is fixed and the warp is corrected is stacked.

  The developing unit 24 incorporates six developing devices 24A, 24B, 24C, 24D, 24E, and 24F corresponding to six colors obtained by adding two special colors to CMYK four colors, and the developing devices 24A to 24F. Contains a two-component developer composed of toner of each color and a carrier. As the developing unit 24 is sequentially rotated by 60 degrees, development is performed using toners of CMYK and special colors, and toner images of the respective colors are formed. The toner images of the respective colors are superimposed on each other when transferred to the intermediate transfer belt 25 by the primary transfer roll 26 to form a full-color toner image, and the full-color toner image is transferred to the paper by the secondary transfer device 28. Is done. The six developing devices 24A to 24F are supplied with toner of each color from the toner containers 60A to 60F.

  The paper transport unit 30 transports the paper along the transport path R1 and the front / back reversing path R2. The paper transport unit 30 includes take-out rolls 31A, 31B, and 31C that take out paper from the paper containers 50A, 50B, and 50C, a scooping roll 32A, 32B, and 32C, and first transport rolls 33A and 33B that transport the paper. , 33C, 33D, 33E, 33F and second transport rollers 34A, 34B, a registration roll 35 for feeding the paper to the secondary transfer device 28 in accordance with the timing at which the secondary transfer device 28 transfers the toner image, and the paper A belt conveyor 36 that conveys the toner from the secondary transfer device 28 to the fixing device 29 while adsorbing, discharge rollers 37A and 37B that discharge the sheet to the outside of the copying machine 1, and a switched conveyance that switches the conveyance direction of the sheet. A double-sided conveyance roll 39A, 39B, 39C, 39 for conveying a roll 38 and a sheet along a front / back reversing path R2 for double-sided printing. , A 39E, and 39F.

  Here, each of the rolling rolls 32A to 32C, the first transport rolls 33A to 33F, the second transport rolls 34A and 34B, the discharge rolls 37A and 37B, the switching transport roll 38, and the double-sided transport rolls 39A to 39F is a circumferential surface. A pair of rotating members that rotate in a state where they are in contact with each other, but unless otherwise specified, a pair of rotating members is simply referred to as a roll. The pair of rotating members conveys the sheet by sandwiching the sheet between the peripheral surfaces.

  The paper accommodated in the paper containers 50A to 50C is taken out by the take-out rolls 31A to 31C, is wound by the separating rolls 32A to 32C, and is transported by the first transport rolls 33A to 33F and the second transport rolls 34A and 34B. R1 is conveyed in the direction of arrow C in the figure. Thereafter, the sheet is fed to the secondary transfer device 28 by the registration roll 35, and the toner image is transferred. The sheet is conveyed to the fixing unit 29 by the belt conveyance unit 36, and the toner is fixed on the sheet. Thereafter, the warp is corrected by the warp correction device 70, discharged by the discharge rollers 37 </ b> A and 37 </ b> B, and stacked on the stacking tray 80.

  When double-sided printing is executed in the copying machine 1, the paper transport unit 30 transports the paper along the front / back reversing path R2 branched from the transport path R1 and returning to the transport path R1, and the paper is transported along the front / back reversing path R2. The front and back surfaces are reversed by turning back the progress of. More specifically, the sheet passing through the warp correction device 70 is conveyed in the reverse direction by switching the conveyance direction of the switching conveyance roll 38 while being conveyed by the switching conveyance roll 38, and subsequently, the double-sided conveyance rolls 39 </ b> A to 39 </ b> A to 39 </ b> A. By 39F, it is conveyed in the direction of arrow D in the figure along the front / back reversing path R2. The paper transported through the front / back reversing path R2 returns to the transport path R1, passes through the second transport rolls 34A and 34B, and the registration roll 35 again, and is transferred to the back surface, that is, the surface on which the toner image has not been transferred by the secondary transfer device 28. The image is transferred.

  The control unit 40 controls the operation of each unit provided in the image reading unit 10, the image forming unit 20, and the paper transport unit 30. The control unit 40 controls, for example, a motor that drives each roll of the paper transport unit 30. The control unit reduces the power consumption consumed by the entire copier 1 and efficiently distributes the rated power allocated to the entire copier 1 so that sensors (not shown) arranged at various locations of the copier 1 are allocated. The driving state of each unit is switched according to the detection result and the time measurement result. More specifically, the copying machine 1 as a whole drives a portion that contributes to image formation and drives a portion that does not contribute to image formation even during image formation on paper. To stop. For example, for each roll of the paper transport unit 30 disposed in the transport path R1 and the front / back reversing path R2, the roll that has completed transport of the paper stops driving. As a result, the power consumption of the copying machine 1 is reduced by the power consumption of the roll whose driving is stopped.

  FIG. 2 is an enlarged configuration diagram showing the front / back reversing path portion of the paper transport unit shown in FIG.

  FIG. 2 shows the double-sided conveyance rolls 39A to 39F arranged on the front / back reversing path R2 and the second conveyance roll 34A arranged on the conveyance path R1. Each of the duplex conveying rolls 39A to 39F is a pair of rotating members as described above. One rotating member of each pair of the duplex conveying rolls 39A to 39F is driven by a motor 392 via a belt 391, and the other rotating member is driven to rotate. The six double-sided transport rolls 39A to 39F are driven by one motor 392 and interlocked. The second transport roll 34A is also a pair of rotating members, one rotating member is driven by a motor 341, and the other rotating member is driven to rotate.

  A guide member 300 is provided on the front / back reversing path R2 and the transport path R1. The guide member 300 is provided on both the front and back surfaces of the sheet to be transported, and extends along the front / back reversing path R2 and the transport path R1. In other words, the front / back reversing path R2 and the transport path R1 are defined by the guide member 300.

  In the front / back reversing path R2, the section in which the double-sided conveyance rolls 39A to 39F are arranged extends substantially horizontally and substantially linearly. Of the six double-sided conveyance rolls 39A to 39F, the most downstream in the conveyance direction in which the paper is conveyed Downstream of the double-sided conveyance roll 39F, the sheet is bent because it joins the conveyance path R1 extending upward from the sheet storage units 50A to 50C (see FIG. 1). More specifically, the front / back reversing path R2 is bent between the most downstream duplex conveying roll 39F and the second conveying roll 34A. The front / back reversing path R2 is bent substantially 90 ° between the double-sided conveyance roll 39F and the second conveyance roll 34A. The guide members 300 are disposed on both sides of the bent portion R2a of the front / back reversing path R2, and guide the sheet to the second transport roll 34A along the bent portion R2a of the front / back reversing path. Hereinafter, the bent portion R2a of the front / back reversing path R2 is referred to as a curved path R2a. Inside the curved path R <b> 2 a, a columnar rotating body 311 is arranged along with the guide member 300.

  The inner side of the path means the side where there is a straight line connecting the area where the rotating members of the first transport rotating member pair are in contact with the area where the rotating members of the second transport rotating member are in contact with the path. The outside of the path means the opposite side of the inside.

  FIG. 3 is an enlarged configuration diagram illustrating a curved path of the front and back inversion paths illustrated in FIG. FIG. 4 is a perspective view showing members arranged around the curved path shown in FIG.

  Here, with reference to FIG. 3 and FIG. 4, the members around the curved path R2a will be described in more detail.

  The second transport roll 34A is a pair of columnar rotating members 343 and 344. The rotating members 343 and 344 are deformed by being pressed against each other in the pinching area N1 for pinching the paper, and are in surface contact with each other. Rotating members 343 and 344 rotate in the direction of arrow E in FIG. 3 and carry the paper by sandwiching the paper on which the image is formed during double-sided printing. The double-sided conveyance roll 39F is a pair of cylindrical rotating members 393 and 394. The rotating members 393 and 394 are deformed by being pressed against each other in the sandwiching area N2 for sandwiching the paper, and are in surface contact with each other. Rotating members 393 and 394 rotate in the direction of arrow F in FIG. 3, and during double-sided printing, the paper on which an image is formed is sandwiched between the contacted peripheral surfaces to transport the paper and feed it into the curved path R2a.

  The guide member 300 is arranged along the curved path R2a shown in FIG. 3 in the front / back reversing path R2. More specifically, three guide members 301, 302, 303 made of bent plates are arranged inside the curved path R <b> 2 a, and three guide members 304, 305, 306 are also arranged on the opposite outer side. Is arranged. Here, the inside of the curved path R2a means the side where the straight line P0 connecting the two sandwiching regions N1 and N2 is located with respect to the curved path R2a. FIG. 4 shows a state in which the guide member 305 disposed in the middle of the three outer guide members 304, 305, and 306 is removed.

  Inside the curved path R2a, a rotating body 311 is arranged along with the three inner guide members 301, 302, and 303. The rotating body 311 is rotatably supported by the bearing member 312. The bearing member 312 is fixed to the guide member 302 arranged in the middle of the three inner guide members 301, 302, and 303 with screws. The surface on the curved path R2a side of the bearing member 312 has a role as a guide member together with the three guide members 301, 302, and 303.

  When the double-sided conveyance roll 39F conveys the sheet and feeds it into the curved path R2a, the fed sheet is divided into the three inner guide members 301, 302, 303 and the bearing member 312 and the three outer guide members 304, 305. , 306 is guided to the second conveying roll 34A, that is, the pair of rotating members 343, 344 while sliding along the guide members 301 to 306 and the bearing member 312. At this time, the sheet has the surface on which the image has already been formed facing the curved curved path R2a. The sheet that has reached the second conveyance roll 34A is further conveyed while being sandwiched between the circumferential surfaces of the rotating members 343 and 344.

  Here, the part which conveys a sheet | seat shown in FIG. 3 and FIG. 4 is equivalent to one Embodiment of the medium conveying apparatus of this invention. Moreover, the 2nd conveyance roll 34A corresponds to an example of the 1st conveyance rotation member pair said to this invention, and the double-sided conveyance roll 39F corresponds to an example of the 2nd conveyance rotation member pair said to this invention. The paper corresponds to an example of a recording medium according to the present invention.

  The rotation of the duplex conveying roll 39F and the second conveying roll 34A is controlled by the control unit 40. However, in the copying machine 1 of the present embodiment, the power consumption of the entire copying machine 1 is suppressed, and the power consumption reaches the rated value. In order not to exceed this, control is performed to concentrate electric power on a portion necessary for image formation on a sheet. More specifically, the double-sided transport roll 39F arranged upstream of the curved path R2a in the direction in which the paper is transported saves power after the front end of the paper being transported reaches the second transport roll 34A in order to save power. The driving of the rotation by the motor 392 (see FIG. 2) stops before the rear end of the double-sided conveyance roll 39F is separated. That is, the double-sided transport roll 39F arranged upstream stops driving even when the paper is sandwiched, and then the paper is transported so as to be pulled by the second transport roll 34A downstream.

  The double-sided conveyance roll 39F has a built-in one-way clutch that enables idling, and even after rotation stops, the double-sided conveyance roll 39F rotates in the direction of arrow F in FIG. to continue. However, this time, the sheet moves along the curved path R2a so as to be pulled by the second conveyance roll 34A while receiving the resistance of the double-side conveyance roll 39F. At this time, the paper is strongly pressed inward. When the surface on which the sheet image is formed moves so as to strongly press against the three guide members 301, 302, 303 and the bearing member 312 inside the curved path R2a, the surface on which the sheet image is formed becomes. Rubbing, scraping the image and causing image distortion.

  In particular, since the thick paper has a stronger stiffness (elasticity) than the thin paper, the upstream side in the transport direction is in a state where the portions sandwiched between the rotating members 343 and 344 to be transported extend in a substantially vertical direction. When bent by hitting any part of the guide members 301 to 306, the guide members 301 to 306 are not shaped along the shape of the guide members 301 to 306 but are conveyed so as to stretch outward. For this reason, a part of the paper is concentrated and pressed against a part of the inner three guide members 301, 302, and 303. On the other hand, since thin paper is weak, it cannot be stretched to the outside, and is conveyed along the inner guide members 301 to 306. Since the force applied to the site is dispersed, the image is hardly damaged. For thin paper with weak stiffness, contact with the guide members 301, 302, and 303 provides paper conveyance performance.

  Inside the curved path R2a, a rotating body 311 is arranged along with the guide members 301, 302, and 303, and the rotating body 311 rotates when the sheet contacts. Therefore, even for thick paper, image distortion due to paper sliding is avoided.

More specifically, the rotating body 311 is disposed so as to protrude further toward the outer side of the curved path R2a than the inner guide members 301, 302, and 303. Here, the paper is generally classified into thin paper, plain paper, and thick paper with basis weights of 52 to 81 g / m ² , 82 to 105 g / m ² , and 106 to 163 g / m ² , respectively. The position of the rotating body 311 is such that paper having a basis weight of 106 g / m ² or more is prevented from coming into contact with the inner guide members 301, 302, and 303, and the basis weight is 81 g / m ² or less. Is set to a position protruding toward the outer side of the curved path R2a to the extent that it contacts the inner guide members 301, 302, and 303. A sheet having a basis weight of 82 to 105 g / m ² may or may not contact the guide members 301, 302, and 303. Therefore, the position of the rotating body 311 is such that the paper having a basis weight of 82 to 105 g / m ² may or may not contact the guide members 301, 302, and 303 depending on environmental conditions other than the basis weight. The position of

  Here, the positional relationship between the rotating body 311 and the guide members 301, 302, 303, 304, 305, 306 will be described in detail.

  A circle P <b> 1 illustrated in FIG. 3 is a circle circumscribing the rotating body 311. The straight line P2 is a straight line connecting the upstream end N2a and the downstream end N2b in the paper conveyance direction of the sandwiching region N2 in the rotating members 393 and 394 of the double-sided conveyance roll 39F, and the straight line P3 is the second line P3. This is a straight line connecting the upstream end N2a and the downstream end N2b of the clamping region N1 in the rotation members 343 and 344 of the transport roll 34A. The circle P1 is in contact with the straight line P2 and the straight line P3. The guide members 301, 302, 303, 304, 305, and 306 in the curved path R2a include an arc connecting the first straight line P2 and the second straight line P3 on the circle P1, a first straight line P2, and a second straight line P3. It is placed at a position that avoids the curve.

  Here, the positional relationship between the rotating body 311 and the guide members 301, 302, and 303 will be described in more detail.

  FIG. 5 is a diagram illustrating the positional relationship of members around the curved path shown in FIG. 5, among the members shown in FIG. 3, the guide members 301, 302, 303 inside the curved path R2a, the rotating body 311, the bearing member 312, the rotating members 343, 344 of the second transport roll 34A, and both surfaces Rotating members 393 and 394 of the transport roll 39F are shown. For the inner guide members 301, 302, and 303, only the portion facing the curved path R2a that actually guides the sheet is shown. 5 shows a circle P1, a first straight line P2, and a second straight line P3, as in FIG. Further, FIG. 5 shows the second contact between both the peripheral surface of the rotating member 344 and the peripheral surface of the rotating body 311 arranged on the inner side of the curved path R2a among the rotating members 343 and 344 of the second transport roll 34A. 3 straight lines P4 and a 4th straight line P5 in contact with both of the rotating members 394 disposed on the inner side of the curved path R2a and the peripheral surface of the rotating body 311 among the rotating members 393 and 394 of the double-sided transport roll 39F are shown. Has been.

  In the present embodiment, of the inner guide members 301, 302, and 303, the portion facing the curved path R2a that actually guides the paper is disposed inside the circle P1 and the first straight line P2, and It is arranged closer to the center of the curved path indicated by the alternate long and short dash line R2a than one of the third straight line P4 and the fourth straight line P5.

  Next, how a sheet is conveyed along a curved path formed by members arranged as shown in FIG. 5 will be described.

6, FIG. 7, FIG. 8, and FIG. 9 are diagrams for explaining how the cardboard is conveyed along the curved path shown in FIG. 6 to 9 show how the paper S, which is a thick paper having a basis weight of 106 g / m ² , passes through the curved path shown in FIG. 3 in order of time.

  First, as shown in FIG. 6, the sheet S on which an image is formed by the image forming unit 20 (see FIG. 1) is conveyed to the rotating members 393 and 394 of the double-sided conveyance roll 39F, and the outer guide member 304 and the inner guide member 304 are arranged inside. It is guided by the guide member 301 and proceeds in a bent state. At this time, the sheet S moves by sliding the surface on which the image is formed on the inner guide member 301. However, at this time, the sheet S is in a state of being conveyed only to the rotating members 393 and 394, and thus no tension or the like is generated. Accordingly, the force with which the sheet S is pressed against the guide member 301 is only an elastic force generated by bending, and the sliding of the sheet S is such that the image is not disturbed.

  Next, as shown in FIG. 7, when the sheet S is further conveyed, the sheet S advances while being guided by the guide member 305 downstream of the outer guide member 304.

  Next, as illustrated in FIG. 8, when the sheet S is further conveyed, the sheet S comes into contact with the rotating body 311. The rotating body 311 obtains a driving force from the paper S and starts rotating.

  Next, as shown in FIG. 9, when the paper S is further transported, the paper S reaches the second transport roll 34A. It is sandwiched and transported between the rotating members 343 and 344 of the second transport roll 34A. When the paper S is driven by the second transport roll 34A, the rotation members 393 and 394 of the double-side transport roll 39F stop driving the rotation by the motor 392 (see FIG. 2) while the paper S is sandwiched between them. . The rotating members 393 and 394 are each provided with a one-way clutch, and continue to rotate by obtaining a force from the sheet S conveyed to the rotating members 343 and 344 of the second conveying roll 34A. At this time, tension is generated on the paper S due to the load of the double-sided conveyance roll 39F. The paper S tends to be closer to the inside by the amount of tension.

  However, since the paper S, which is a thick paper, has a stronger elasticity than the thin paper described later, the paper S is bent so as to bend from a portion sandwiched between the peripheral surfaces of the rotating members 343 and 344 of the second transport roll 34A. It does not press against the inner guide members 301, 302, 303 but presses against the rotating body 311. More specifically, the sheet S is sandwiched between the circumferential surfaces of the rotating members 343 and 344 of the second transport roll 34A, and the sandwiched portion extends in a substantially vertical direction in contact with the circumferential surface, that is, The posture is substantially perpendicular to a line passing through the centers of the rotating members 343 and 344, and the shape is bent toward the double-sided conveyance roll 39F. For this reason, the sheet S does not have a shape along the inner guide members 301, 302, and 303 arranged at the positions described with reference to FIG. Press against the rotating body 311.

  In the state shown in FIG. 9, the sheet S strongly presses against the rotating body 311 by the above-described tension, but the rotating body 311 rotates when the sheet S comes into contact with it, so Disturbance is avoided.

  Here, a comparative example having no rotating body will be described.

  FIG. 10 is a diagram illustrating a state in which cardboard is conveyed along a curved path of a comparative example that does not have a rotating body. The paper transport position shown in FIG. 10 is the same as in FIG. Further, the configuration shown in FIG. 10 is different from the configuration of the present embodiment shown in FIG. 9 in that the rotating body 311 is not provided, and the other points are the same as the configuration shown in FIG.

  In the comparative example shown in FIG. 10, the rotation of the rotation members 393 ′ and 394 ′ of the double-sided conveyance roll is performed while the sheet S is conveyed while being sandwiched between the circumferential surfaces of the rotation members 343 ′ and 344 ′ of the second conveyance roll. When driving is stopped, the tensioned sheet S is bent and a part of the sheet S is concentrated and pressed against the inner guide member 301 ′. For this reason, the paper is more slid on the guide member 301 ′, which causes image disturbance.

  On the other hand, in the configuration of the present embodiment, as shown in FIG. 9, the disturbance of the image of the paper S, which is a thick paper, due to sliding is avoided.

  Next, the case of thin paper will be described.

11, FIG. 12, FIG. 13, FIG. 14 and FIG. 15 are diagrams for explaining how thin paper is conveyed along the curved path shown in FIG. In FIG. 11 to FIG. 15, a state in which the paper S which is a thin paper having a basis weight of 81 g / m ² or less passes is shown in time order.

  The state shown in FIGS. 11 to 14 for the thin paper is almost the same as the state shown in FIGS. 6 to 9 for the thick paper. Since the sheet S, which is a thin sheet, has less elasticity than the thick sheet, the sheet that hits the outer guide members 304, 305, and 306 when being conveyed by being pushed by the duplex conveying roll 39F. The tip of S is likely to bend in the path and cause a paper jam. However, the inner guide members 301, 302, and 303 in this embodiment are arranged closer to the center of the route than one of the third straight line P4 and the fourth straight line P5 shown in FIG. The inner guide members 301, 302, and 303 are close to the outer guide members 304, 305, and 306 to such an extent that the leading edge of the sheet can be stably conveyed without being bent in the path.

  FIG. 15 shows a state in which the sheet S, which is a thin sheet, is conveyed while being sandwiched between the rotating members 343 and 344 of the second conveying roll 34A.

  As shown in FIG. 15, when the paper S is driven by the second transport roll 34A, the rotating members 393 and 394 of the double-side transport roll 39F are rotated by the motor 392 (see FIG. 2) with the paper S sandwiched therebetween. Is stopped. At this time, tension is generated on the paper S due to the load of the double-sided conveyance roll 39F. The paper S tends to be closer to the inside by the amount of tension.

  However, since the sheet S, which is a thin sheet, has less elasticity (roughness) than the thick sheet, the sheet S bends in a shape along the inner guide members 301, 302, and 303, and the rotating body 311 and the inner guide member 301, It pushes against the whole 302,303. For this reason, the paper S, which is a thin paper, is prevented from being pressed against a part, and the pressing force is dispersed. Therefore, the disturbance of the image on the paper S due to the sliding is avoided.

  In the above-described embodiment, the medium transport device provided in the front / back reversing path R2 has been described as an example. However, the medium transport device according to the present invention is not limited to this, and for example, an image such as a stapler or a bend. It may be used for a conveyance path during post-processing of the forming process.

  In the above-described embodiment, a color copying machine is shown as an example of the image forming apparatus. However, the image forming apparatus referred to in the present invention is not limited to this, and may be, for example, a monochrome copying machine, a printer, or a facsimile.

  In the above-described embodiment, the paper sheet has been described as an example of the recording medium. However, the recording medium referred to in the present invention is not limited to this, and may be a resin sheet, for example.

  In the above-described embodiments, the electrophotographic structure for developing the electrostatic latent image with toner is shown as an example of the image forming unit according to the present invention. However, the image forming unit according to the present invention is not limited to this. For example, an inkjet method may be used.

DESCRIPTION OF SYMBOLS 1 Copier 20 Image formation part 30 Paper conveyance part 34A, 34B Conveyance roll 39A, 39B, 39C, 39D, 39E, 39F Double-sided conveyance roll 301,302,303 Inner guide member 304,305,306 Outer guide member 311 Rotation Body 343, 344 Rotating member 393, 394 Rotating member P1 Circle P2 First straight line P3 Second straight line P4 Third straight line P5 Fourth straight line R2a Curved path S Paper

Claims (6)

A pair of rotating members that rotate in a state where the peripheral surfaces are in contact with each other, the first pair of rotating rotating members that convey by sandwiching a sheet-like recording medium having an image formed on the surface;
When the recording medium comes into contact and slides, the recording medium is guided to the first transport rotation member pair along a curved path. The recording medium has a surface on which an image is formed on both sides of the path. A guide member disposed on both the inside and the outside of the path that is guided toward the inside of the path;
The recording medium is a second conveyance rotating member pair composed of a rotating member that rotates in a state where the peripheral surfaces are in contact with each other, and the recording medium is conveyed by sandwiching the recording medium and sent to the path. A second conveyance rotation member pair whose rotation is finished before the recording medium is separated from the second conveyance rotation member after reaching the second conveyance rotation member pair;
Provided inside the path alongside the guide member, and a rotating body that rotates when the recording medium comes into contact with a peripheral surface,
The guide member includes an upstream end and a downstream end in a transport direction in which the recording medium is transported in a sandwiching region in which the rotating members constituting the first transport rotating member pair come into contact with each other to sandwich the recording medium. An upstream end in a transport direction in which the recording medium is transported, in a sandwiching region in which the first straight line connecting the ends and the rotating member forming the second transport rotating member pair come into contact with each other to sandwich the recording medium And a second straight line connecting the downstream end and a circular arc connecting the first straight line and the second straight line on a circle in contact with the first straight line, the second straight line, and the peripheral surface of the rotating body. A medium conveying apparatus characterized by being provided at a position avoiding the curved line. The guide member arranged inside the path along with the rotating body has the recording medium in the sandwiching area in which the rotating members constituting the first transport rotating member pair come into contact with each other to sandwich the recording medium. The first straight line connecting the upstream end and the downstream end in the transport direction for transport, and the sandwiching region in which the rotating members forming the second transport rotating member pair come into contact with each other to sandwich the recording medium, A second straight line connecting the upstream end and the downstream end in the transport direction for transporting the recording medium, the first straight line, the second straight line, and the first straight line on a circle in contact with the circumferential surface of the rotating body. A guide member disposed on the inner side of a curve composed of a straight line and an arc connecting the second straight line, and the first transport rotation member pair disposed closer to the inner side of the path. A third member in contact with both the circumferential surface of the rotating member and the circumferential surface of the rotating body; More than at least one of the line and the fourth straight line in contact with both the peripheral surface of the second rotating member and the peripheral surface of the rotating body disposed on the inner side of the path among the pair of second conveying rotating members The medium conveying apparatus according to claim 1, wherein the medium conveying apparatus is disposed near the outside of the path.   The rotating body prevents the recording medium having a basis weight of 106 g / m 2 or more from coming into contact with the inner guide member disposed inside the path among the guide members, and the basis weight is 81 g / m 2 or less. 3. The medium conveyance according to claim 1, wherein the rotating body protrudes closer to the outside of the path than the inner guide member to the extent that the recording medium contacts the inner guide member. apparatus. A pair of rotating members that rotate in a state where the peripheral surfaces are in contact with each other, the first pair of rotating rotating members that convey by sandwiching a sheet-like recording medium having an image formed on the surface;
When the recording medium comes into contact and slides, the recording medium is guided to the first transport rotation member pair along a curved path. The recording medium has a surface on which an image is formed on both sides of the path. A guide member disposed on both the inside and the outside of the path that is guided toward the inside of the path;
The recording medium is a second conveyance rotating member pair composed of a rotating member that rotates in a state where the peripheral surfaces are in contact with each other, and the recording medium is conveyed by sandwiching the recording medium and sent to the path. A second conveyance rotation member pair whose rotation is finished before the recording medium is separated from the second conveyance rotation member after reaching the second conveyance rotation member pair;
A rotating body provided inside the path alongside the guide member and rotating when the recording medium comes into contact with a peripheral surface, and a recording medium having a basis weight of 106 g / m 2 or more is the guide member. More than the inner guide member, the recording medium having a basis weight of 81 g / m2 or less is in contact with the inner guide member so as to prevent contact with the inner guide member disposed inside the path. A medium conveying apparatus comprising a rotating body protruding toward the outside of the path. An image forming unit that forms an image on the surface of a sheet-like recording medium;
A pair of rotating members that rotate in a state where the peripheral surfaces are in contact with each other, and a first conveying rotating member pair that conveys by sandwiching a recording medium on which an image is formed by the image forming unit;
When the recording medium comes into contact and slides, the recording medium is guided to the first transport rotation member pair along a curved path. The recording medium has a surface on which an image is formed on both sides of the path. A guide member disposed on both the inside and the outside of the path that is guided toward the inside of the path;
The recording medium is a second conveyance rotating member pair composed of a rotating member that rotates in a state where the peripheral surfaces are in contact with each other, and the recording medium is conveyed by sandwiching the recording medium and sent to the path. A second conveyance rotation member pair whose rotation is finished before the recording medium is separated from the second conveyance rotation member after reaching the second conveyance rotation member pair;
Provided inside the path alongside the guide member, and a rotating body that rotates when the recording medium comes into contact with a peripheral surface,
The guide member includes an upstream end and a downstream end in a transport direction in which the recording medium is transported in a sandwiching region in which the rotating members constituting the first transport rotating member pair come into contact with each other to sandwich the recording medium. An upstream end in a transport direction in which the recording medium is transported, in a sandwiching region in which the first straight line connecting the ends and the rotating member forming the second transport rotating member pair come into contact with each other to sandwich the recording medium And a second straight line connecting the downstream end and a circular arc connecting the first straight line and the second straight line on a circle in contact with the first straight line, the second straight line, and the peripheral surface of the rotating body. An image forming apparatus, wherein the image forming apparatus is provided at a position avoiding the curved line. An image forming unit that forms an image on the surface of a sheet-like recording medium;
A pair of rotating members that rotate in a state where the peripheral surfaces are in contact with each other, the first pair of rotating rotating members that convey by sandwiching a sheet-like recording medium having an image formed on the surface;
When the recording medium comes into contact and slides, the recording medium is guided to the first transport rotation member pair along a curved path. The recording medium has a surface on which an image is formed on both sides of the path. A guide member disposed on both the inside and the outside of the path that is guided toward the inside of the path;
The recording medium is a second conveyance rotating member pair composed of a rotating member that rotates in a state where the peripheral surfaces are in contact with each other, and the recording medium is conveyed by sandwiching the recording medium and sent to the path. A second conveyance rotation member pair whose rotation is finished before the recording medium is separated from the second conveyance rotation member after reaching the second conveyance rotation member pair;
A rotating body provided inside the path alongside the guide member and rotating when the recording medium comes into contact with a peripheral surface, and a recording medium having a basis weight of 106 g / m 2 or more is the guide member. More than the inner guide member, the recording medium having a basis weight of 81 g / m2 or less is in contact with the inner guide member so as to prevent contact with the inner guide member disposed inside the path. An image forming apparatus comprising: a rotating body protruding toward the outside of the path.

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