Conveying device and image forming device

Abstract

The contact pressure of the transport roll located upstream of the alignment roll in the transport direction of the recording medium and the spacing of the transport path downstream of the alignment roll in the transport direction of the recording medium are configured to be constant regardless of the type of recording medium, thereby suppressing the occurrence of poor transport of the recording medium to the transfer section. [Solution] A conveying device 60 is provided with a conveying roll 58 that conveys a recording medium P toward an alignment roll 54, a first guide section 61 that is provided downstream of the conveying roll 58 in the conveying direction of the recording medium P and guides the recording medium P to the alignment roll 54, a second guide section 62 that is provided downstream of the alignment roll 54 in the conveying direction of the recording medium P and guides the recording medium P to a transfer section, a position variable mechanism 70 that changes the positions of the first guide section 61 and the second guide section 62 depending on the type of recording medium P, and a pressure variable mechanism 80 that changes the contact pressure of the conveying roll 58 in conjunction with the first guide section 61 whose position has been changed by the position variable mechanism 70.

Description

[Technical Field]

[0001] The present invention relates to a conveying device and an image forming apparatus. [Background technology]

[0002] Image forming devices equipped with an image forming unit that forms an image on a recording medium and a skew correction unit that corrects skew by abutting the recording medium against a gate on a transport path that transports the recording medium toward the image forming unit have been known for some time (see, for example, Patent Document 1). This skew correction unit includes a transport guide and a movable guide that guide the recording medium above and below the transport path, and the movable guide moves in the thickness direction of the recording medium, separately from the transport unit and the transport guide, to guide the recording medium.

[0003] Also, image forming apparatuses equipped with image processing devices that transfer toner images formed on image carriers onto various types of recording materials have been known for some time (see, for example, Patent Document 2). This image forming apparatus has registration rollers that transport the recording material toward the transfer position of the image processing device at a predetermined timing, a movable guide body that forms a curved pre-transfer path from the registration rollers to the transfer position, and a position changing device that changes the position of the movable guide body to change the path of the curved pre-transfer path.

[0004] Also, there has been known an image forming apparatus in which a guide member consisting of a secondary transfer feed guide that guides the sheet material, which is recording paper, is provided in the section between a registration roller arranged on the upstream side of the conveyance path of the sheet material and a secondary transfer roller arranged on the downstream side (see, for example, Patent Document 3). The secondary transfer feed guide has a sheet correction plate (movable part) that adjusts the front depth of the sheet by moving the part that abuts so that the leading edge of the sheet material is parallel to the sheet width direction that is perpendicular to the conveyance direction, and a part of this plate serves as a correction part that abuts against the sheet material during conveyance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-062194 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-098543 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-323154 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to provide a conveying device that can suppress the occurrence of poor conveyance of a recording medium to a transfer section, compared to when the contact pressure of a pair of conveying rolls, which are located upstream of a pair of alignment rolls in the conveying direction of the recording medium, on the recording medium and the spacing of the conveying path downstream of the pair of alignment rolls in the conveying direction of the recording medium are configured to be constant regardless of the type of recording medium. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, a conveying device of a first aspect of the present invention comprises a pair of alignment rolls that convey a recording medium to a transfer section at a predetermined timing, a pair of conveying rolls that are arranged upstream of the pair of alignment rolls in the conveying direction of the recording medium and convey the recording medium toward the pair of alignment rolls that are stopped from rotating, a first guide section that is arranged downstream of the pair of conveying rolls in the conveying direction of the recording medium and guides the recording medium to the pair of alignment rolls, a second guide section that is arranged downstream of the pair of alignment rolls in the conveying direction of the recording medium and guides the recording medium to the transfer section, a position variable mechanism that changes the positions of the first guide section and the second guide section depending on the type of recording medium, and a pressure variable mechanism that changes the contact pressure of the pair of conveying rolls in conjunction with the first guide section whose position has been changed by the position variable mechanism.

[0008] A second aspect of the transport device according to the present invention is the transport device of the first aspect, wherein the position variable mechanism changes the positions of the first guide portion and the second guide portion depending on the basis weight of the recording medium.

[0009] Furthermore, a third aspect of the conveying device according to the present invention is a conveying device of the first aspect, wherein when the recording medium is paper thinner than cardboard, the position variable mechanism changes the position of the first guide portion so that the space downstream of the pair of conveying rolls in the conveying direction of the recording medium is wider than when the recording medium is cardboard, and changes the position of the second guide portion so that the distance between the conveying paths downstream of the pair of alignment rolls in the conveying direction of the recording medium is narrower than when the recording medium is cardboard, and the pressure variable mechanism changes the contact pressure of the pair of conveying rolls to be lower than when the recording medium is cardboard.

[0010] Furthermore, a fourth aspect of the conveying device according to the present invention is the conveying device of the first aspect, wherein the first guide portion and the second guide portion are configured to move together to change their positions.

[0011] Furthermore, a fifth aspect of the conveying device according to the present invention is the conveying device of the fourth aspect, wherein the first guide section and the second guide section are configured to change their positions by rotating around a rotation axis that is coaxial with the rotation axis of the pair of alignment rolls.

[0012] Furthermore, a sixth aspect of the conveying device according to the present invention is the fourth aspect of the conveying device, wherein the first guide portion and the second guide portion are configured to change their positions by rotating around the downstream end of the first guide portion in the conveying direction of the recording medium.

[0013] Furthermore, a seventh aspect of the conveying device according to the present invention is the conveying device of the first aspect, wherein the second guide portion has an extension portion at an end facing the conveying path of the recording medium, the extension portion extending toward the pair of alignment rolls.

[0014] In addition, an eighth aspect of the conveying device according to the present invention is a conveying device of the first aspect, wherein the pressure variable mechanism has two spring members with different spring forces, and the contact pressure of the pair of conveying rolls can be changed by using one or both of the two spring members.

[0015] Furthermore, a ninth aspect of the conveying device according to the present invention is the conveying device of the eighth aspect, wherein the two spring members are formed in a "U" shape and are configured to press both ends of the shaft portion of one of the pair of conveying rolls that protrude axially outward toward the other conveying roll.

[0016] In addition, a tenth aspect of the image forming apparatus according to the present invention includes a conveying device according to any one of the first to ninth aspects, a transfer unit that transfers a toner image onto a recording medium conveyed by the conveying device, and a fixing device that fixes the toner image transferred by the transfer unit onto the recording medium. [Effects of the Invention]

[0017] According to the first aspect of the invention, the contact pressure of a pair of conveying rolls arranged upstream of the pair of alignment rolls in the conveying direction of the recording medium and the spacing of the conveying path downstream of the pair of alignment rolls in the conveying direction of the recording medium can be made constant regardless of the type of recording medium, thereby suppressing the occurrence of poor conveying of the recording medium to the transfer section.

[0018] According to the second aspect of the invention, the contact pressure of the pair of conveying rolls against the recording medium and the spacing of the conveying path downstream of the pair of alignment rolls in the conveying direction of the recording medium can be made constant regardless of the basis weight of the recording medium, thereby suppressing the occurrence of poor conveying of the recording medium to the transfer section.

[0019] According to the invention of the third aspect, even when the recording medium is paper that is thinner than cardboard, the occurrence of poor transport of the paper to the transfer section can be suppressed compared to when the positions of the first guide section and the second guide section are the same as when the recording medium is cardboard and the contact pressure of the pair of transport rolls is the same as when the recording medium is cardboard.

[0020] According to the fourth aspect of the invention, the number of parts can be reduced and the position-adjusting mechanism can be simplified compared to when the first guide section and the second guide section are configured to move separately to change their positions.

[0021] According to the fifth aspect of the invention, the positions of the first guide section and the second guide section can be changed with greater precision than when the first guide section and the second guide section are configured so that their positions are changed by rotating around the downstream end of the first guide section in the recording medium transport direction.

[0022] According to the sixth aspect of the invention, the position of the second guide section can be easily changed compared to when the first guide section and the second guide section are configured to change their positions by rotating around a rotation axis that is coaxial with the rotation axis of a pair of alignment rolls.

[0023] According to the seventh aspect of the invention, the occurrence of transport problems in the recording medium sent out by the pair of alignment rolls can be suppressed compared to when the second guide section has an extension section at the end facing the transport path of the recording medium that extends toward the opposite side from the pair of alignment rolls.

[0024] According to the eighth aspect of the invention, the configuration of the pressure variable mechanism can be simplified compared to when the pressure variable mechanism is configured with an electric actuator.

[0025] According to the invention of the ninth aspect, it is easier to assemble the spring members than when the configuration is such that both ends of the shaft portion of one of a pair of conveying rolls that protrude axially outward are pressed toward the other conveying roll by individual springs.

[0026] According to the invention of the 10th aspect, the contact pressure of a pair of transport rolls arranged upstream of the pair of alignment rolls in the transport direction of the recording medium and the spacing of the transport path downstream of the pair of alignment rolls in the transport direction of the recording medium are constant regardless of the type of recording medium, and the occurrence of poor image quality due to poor transport of the recording medium to the transfer section can be suppressed compared to when these are configured to be constant regardless of the type of recording medium. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a schematic side view showing the overall configuration of an image forming apparatus according to a first embodiment. [Figure 2] FIG. 2 is a schematic perspective view showing a guide portion and a pressure variable mechanism of the transport device according to the first embodiment. [Figure 3] 4 is a schematic side view showing an enlarged view of the state of the position variable mechanism when the conveying device according to the first embodiment conveys cardboard. FIG. [Figure 4] 4 is a schematic side view showing an enlarged view of the state of the position variable mechanism when plain paper is transported by the transport device according to the first embodiment. FIG. [Figure 5] 10 is a schematic side view showing an enlarged view of the state of the position variable mechanism when a cardboard is conveyed by the conveying device according to the second embodiment. FIG. [Figure 6] 10 is a schematic side view showing an enlarged view of the state of the position variable mechanism when plain paper is transported by the transport device according to the second embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. For ease of explanation, the arrow UP shown in Fig. 1 indicates the upward direction of the image forming apparatus 10, the arrow LH indicates the leftward direction of the image forming apparatus 10, and the direction toward the front of the paper is the forward direction of the image forming apparatus 10. In addition, hereinafter, the upstream side in the transport direction of recording paper P (see Figs. 3 to 6) as an example of a recording medium may be simply referred to as the "upstream side," and the downstream side in the transport direction may be simply referred to as the "downstream side."

[0029] <<First Embodiment>> First, a first embodiment will be described. As shown in Fig. 1, an image forming apparatus 10 is, as an example, an electrophotographic type that forms a toner image on a recording paper P. The image forming apparatus 10 includes an image forming section 12, a storage section 14, a conveying section 16 (including a conveying device 60), and a fixing device 18 within an apparatus main body 11. Each section of the image forming apparatus 10 (the image forming section 12, the conveying section 16, and the fixing device 18) will be described below.

[0030] <Image forming section> The image forming unit 12 has a function of forming a toner image on recording paper P. Specifically, the image forming unit 12 has a toner image forming unit 20 and an intermediate transfer device 30. In this embodiment, examples of recording paper P include cardboard and plain paper that is thinner than cardboard. In this embodiment, "cardboard" refers to paper with a basis weight of, for example, 300 g / m 2 The above is the paper.

[0031] [Toner image forming unit] 1, a plurality of toner image forming units 20 are provided to form toner images for each color. In this embodiment, toner image forming units 20Y, 20M, 20C, and 20K for a total of four colors, yellow (Y), magenta (M), cyan (C), and black (K), are provided.

[0032] Since the toner image forming units 20 of each color have the same configuration, only the components of the yellow toner image forming unit 20Y are designated by reference numerals in Fig. 1. Also, toner supply devices 28Y, 28M, 28C, and 28K that supply toner to each developing device 26, which will be described later, are provided inside the device main body 11.

[0033] The toner image forming unit 20 for each color has a photosensitive drum 22 that rotates in one direction (for example, counterclockwise in FIG. 1) with the front-to-rear direction as its axial direction. The toner image forming unit 20 for each color also has, in order from the upstream side in the rotation direction of the photosensitive drum 22, a charger 24, an exposure device 25, a developing device 26, and a removal device 27.

[0034] In the toner image forming unit 20 for each color, a charger 24 charges the outer peripheral surface of the photosensitive drum 22. An exposure device 25 exposes the outer peripheral surface of the photosensitive drum 22 charged by the charger 24 to light, thereby forming an electrostatic latent image on the outer peripheral surface of the photosensitive drum 22. A developing device 26 develops the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 22 by the exposure device 25, thereby forming a toner image. A removal device 27 removes toner remaining on the outer peripheral surface of the photosensitive drum 22 after the toner image is transferred to a transfer belt 40, which will be described later.

[0035] [Intermediate transfer device] 1, the intermediate transfer device 30 includes a primary transfer roll 32 as an example of a primary transfer body whose axial direction is the front-to-rear direction, a transfer belt 40 as an example of an intermediate transfer body, and a secondary transfer roll 44 as an example of a secondary transfer body whose axial direction is the front-to-rear direction. That is, the intermediate transfer device 30 is configured to primarily transfer toner images formed on the outer peripheral surfaces of the photosensitive drums 22 of each color onto the transfer belt 40 in an overlapping manner, and then secondarily transfer the overlapped toner images onto the recording paper P.

[0036] (Primary transfer roll) 1, the primary transfer roll 32 transfers the toner images formed on the outer circumferential surfaces of the photosensitive drums 22 of each color in a multiplicity onto the outer circumferential surface of the transfer belt 40 at a primary transfer position between the photosensitive drums 22 and the primary transfer roll 32. In this embodiment, a primary transfer voltage is applied between the primary transfer roll 32 and the photosensitive drums 22, so that the toner images formed on the outer circumferential surfaces of the photosensitive drums 22 are transferred in a multiplicity onto the outer circumferential surface of the transfer belt 40 at the primary transfer position.

[0037] (Transfer belt) 1, transfer belt 40 is annular, with a toner image transferred to its outer peripheral surface, and its orientation is determined by being wound around a drive roll 34, a tension roll 36, and a backup roll 38, whose axial direction is the front-to-rear direction. Drive roll 34 is configured to be driven to rotate by a drive unit (not shown), and causes transfer belt 40 to rotate in the direction of arrow A (clockwise in FIG. 1) at a predetermined speed. A cleaning device 42 that cleans the outer peripheral surface of transfer belt 40 is provided on the opposite side of drive roll 34 across transfer belt 40.

[0038] The backup roll 38 faces the secondary transfer roll 44 with the transfer belt 40 sandwiched therebetween. The contact area where the secondary transfer roll 44 and the transfer belt 40 come into contact, in other words, the area where the recording paper P is sandwiched between the secondary transfer roll 44 and the transfer belt 40, forms a nip area. This nip area forms a secondary transfer position T, which is an example of a transfer section where a toner image is transferred from the transfer belt 40 to the recording paper P.

[0039] <Fixing device> 1, the fixing device 18 has a heating roll 46 as an example of a heating member, whose axial direction is the front-to-rear direction, and a pressure roll 47 as an example of a pressure member, whose axial direction is the front-to-rear direction. The fixing device 18 is configured to fix the toner image transferred to the recording paper P by the secondary transfer roll 44 to the recording paper P by sandwiching the recording paper P between the heating roll 46 and the pressure roll 47, which rotate in opposite directions, and applying heat and pressure to the recording paper P. Downstream of the fixing device 18, there is provided an ejection roll 48, whose axial direction is the front-to-rear direction, for ejecting the recording paper P with the fixed toner image to an ejection section 50 provided at the top of the device main body 11.

[0040] <Transportation section> 1, a plurality of storage sections 14 are provided in the lower part of the device main body 11, each storing recording paper P sorted by size and type. Downstream of each storage section 14, a paper feed roll 51 is provided with its axial direction extending in the front-to-rear direction, and sends the recording paper P stored in the storage section 14 to the transport path of the transport section 16. Downstream of the paper feed roll 51, a plurality of pairs of transport rolls 52 are provided with their axial direction extending in the front-to-rear direction, each rotating in opposite directions to transport the recording paper P one sheet at a time.

[0041] A pair of alignment rolls 54 is provided downstream of the most downstream pair of transport rolls 52, with its axis aligned in the front-to-rear direction, for transporting the recording paper P supplied from the storage unit 14 to the secondary transfer position T at a predetermined transfer timing. When the rotation of this pair of alignment rolls 54 is stopped, the recording paper P is sandwiched between the pair of transport rolls 52 and transported, forming a so-called loop of the recording paper P on the upstream side, thereby correcting skew. The recording paper P whose skew has been corrected is sent out by the pair of alignment rolls 54, which rotate in opposite directions, to the secondary transfer position T where the transfer belt 40 and secondary transfer roll 44 come into contact, in time with the transfer timing.

[0042] Further, on the left side of the discharge roll 48, during double-sided printing in which an image is also formed on the back side of the recording paper P, a pair of transport rolls 56 and a pair of transport rolls 58 are provided with their axial direction extending in the front-to-rear direction to transport the recording paper P again to the alignment roll 54. A plurality of pairs of transport rolls 56 are provided, and a single pair of transport roll 58 is provided.

[0043] The recording paper P is transported along a reversing path by multiple pairs of transport rolls 56 and turned over, and then the pair of transport rolls 58 located most downstream transports the recording paper P again toward the pair of alignment rolls 54 whose rotation is stopped. Note that as this pair of transport rolls 58 transports the recording paper P while nipping it, a so-called loop is formed by the recording paper P upstream of the alignment rolls 54 whose rotation is stopped, and any skew in the recording paper P is corrected.

[0044] [Transportation equipment] Next, the conveying device 60 in the conveying section 16 of the image forming apparatus 10 configured as above will be described in more detail.

[0045] As shown in Figures 2 to 4, the conveying device 60 includes a pair of alignment rolls 54 (see Figures 3 and 4), a pair of conveying rolls 58, a first guide section 61 located downstream of the pair of conveying rolls 58 and guiding the recording paper P to the pair of alignment rolls 54, a second guide section 62 located downstream of the pair of alignment rolls 54 and guiding the recording paper P to a secondary transfer position T (transfer section), a position variable mechanism 70 (see Figures 3 and 4) that changes the position of the first guide section 61 and the second guide section 62 depending on the type (basis weight) of the recording paper P, and a pressure variable mechanism 80 that changes the contact pressure of the pair of conveying rolls 58 in conjunction with the first guide section 61 whose position has been changed by the position variable mechanism 70.

[0046] 2, multiple pairs of transport rolls 58 are arranged at predetermined intervals in the front-to-rear direction, and one (upper) transport roll 58A has a shaft portion 59 protruding outward in the axial direction, both ends 59A of which are rotatably supported by support members 64A provided on an upper guide member 64 that constitutes the transport path for the recording paper P. The other (lower) transport roll 58B (see FIGS. 3 and 4) is rotatably supported by support members (not shown) provided on a lower guide member 63 (see FIGS. 3 and 4) that constitutes the transport path for the recording paper P.

[0047] The pair of transport rolls 58 are configured so that contact pressure is generated when one transport roll 58A is urged toward the other transport roll 58B. Specifically, contact pressure is generated between the pair of transport rolls 58 by the urging forces of two spring members 82 and 84 that constitute the pressure variable mechanism 80.

[0048] The two spring members 82, 84 are formed in a generally U-shape in plan view with different sizes and an opening on the lower side, and are arranged on the inside and outside. That is, the spring members 82, 84 are configured to press both end portions 59A of the shaft portion 59 protruding axially outward of one transport roll 58A from above toward the other transport roll 58B, and are arranged on the inside and outside of both end portions 59A in the axial direction.

[0049] The upper guide member 64 is provided with a flat beam member 65 extending in the front-rear direction with the up-down direction as its normal direction, and a pair of flat support ribs 66 with the front-rear direction as their normal direction are provided downward on the underside of the beam member 65. Each support rib 66 is located above both end portions 59A of the shaft portion 59 of one of the transport rolls 58A, and a cylindrical locking protrusion 66A is provided integrally and protrudes from approximately the center in the up-down direction on the opposing inner surfaces of each support rib 66. A pair of flat locking ribs 67 with the front-rear direction as their normal direction are provided downward on the underside of the beam member 65 between the pair of support ribs 66.

[0050] Therefore, the inner spring member 82 has its bifurcated lower end 82A contacting both ends 59A of the shaft portion 59 of one of the transport rolls 58A from above, its bifurcated middle portion 82B contacting the locking projections 66A from below, and its upper end connecting portion 82C being locked by the pair of locking ribs 67, thereby pressing (biasing) both ends 59A of the shaft portion 59 from above toward the other transport roll 58B. Note that the pair of locking ribs 67 are formed with notches 67A into which the connecting portions 82C of the inner spring member 82 fit, and are configured so that the connecting portions 82C do not come off the locking ribs 67.

[0051] On the other hand, the outer spring member 84 has a bifurcated lower end 84A that contacts both ends 59A of the shaft portion 59 of one of the transport rolls 58A from above, while its bifurcated middle portion 84B contacts the locking protrusion 66A from below, and an upper end connecting portion 84C is locked to an upper end portion above the notch 67A of the locking rib 67, thereby pressing (biasing) both ends 59A of the shaft portion 59 from above toward the other transport roll 58B. The lower end 84A of the outer spring member 84 extends downward further than the lower end 82A of the inner spring member 82, and is in contact with the upper surface of the first guide portion 61.

[0052] 3 and 4, the first guide portion 61 and the second guide portion 62 are configured to move together and change their positions. That is, the first guide portion 61 and the second guide portion 62 are configured to be connected together in a substantially C-shape in the cross-sectional view shown in FIGS. 3 and 4, with the lower end portion including the lower tip portion serving as the first guide portion 61 and the upper tip portion serving as the second guide portion 62. The first guide portion 61 and the second guide portion 62 are configured to change their positions by rotating around an imaginary rotation axis S, which is an example of a rotation axis that is substantially coaxial with the rotation axis 54A of one (left side) of the pair of alignment rolls 54.

[0053] Specifically, the first guide section 61 has a lower surface that bulges downward at an attacking angle, which constitutes part of the transport path, and the lower surface of the first guide section 61 and the upper surface of a lower guide section 78, which will be described later, guide the recording paper P to the pair of alignment rolls 54. The second guide section 62 has an extension section 62B that extends integrally toward the pair of alignment rolls 54 on the lower surface side of an end section 62A that faces the transport path of the recording paper P, and the recording paper P (plain paper) is guided to the secondary transfer position T by the continuous wall surfaces of the end section 62A and the extension section 62B.

[0054] One end (upper end) of a rod-shaped link member 72 configured to be movable substantially vertically is connected to the upper left side of each of the front-rear direction ends of the first guide part 61 so as to be rotatable about its axial direction, which is the front-rear direction. That is, a circular through-hole is formed in one end of the link member 72, and a cylindrical pin 73 provided on the upper left side of each of the front-rear direction ends of the first guide part 61 is fitted into the through-hole. This allows the link member 72 to rotate about the pin 73.

[0055] The other end (lower end) of the link member 72 is configured to be constantly in contact with the circumferential surface of a flat cam member 74 at least by its own weight (preferably by being urged downward). The cam member 74 is fixed to both axial ends of a shaft 76, whose axial direction is the front-to-rear direction, and is configured to rotate integrally with the rotation of the shaft 76.

[0056] The link member 72 and the cam member 74 provided on the shaft 76 are an example of the position variable mechanism 70. The cam member 74 is disposed on the front-rear outer side of the contact area of ​​the recording paper P in the lower guide portion 78, which guides the recording paper P to the pair of alignment rolls 54 together with the first guide portion 61. The shaft 76 is supported at both front-rear end portions of the non-contact area of ​​the recording paper P in the lower guide portion 78.

[0057] 3, when the part where the distance between the outer circumferential surface of the shaft 76 and the outer circumferential surface of the cam member 74 is smallest is located on the upper side, the link member 72 takes the lower position, the first guide part 61 takes the lowered position, the second guide part 62 takes the retracted position where it is retracted from the conveyance path, and the biasing force (pressing force) of the two spring members 82, 84 is applied to both end parts 59A (see FIG. 2) of the shaft part 59 of one conveyance roll 58A. In other words, the contact pressure between the pair of conveyance rolls 58 is maximized.

[0058] As shown in Figure 4, when the part where the distance between the outer peripheral surface of the shaft 76 and the outer peripheral surface of the cam member 74 is greatest is located on the upper side, the link member 72 takes an upper position, so that the first guide portion 61 takes an elevated position and the second guide portion 62 takes an extended position extending into the conveying path, moving only the bifurcated lower end portion 84A of the outer spring member 84 upward away from both ends 59A of the shaft portion 59 of one of the conveying rolls 58A.

[0059] In other words, at this time, only the spring force (pressing force) of the inner spring member 82 is applied to both end portions 59A (see Figure 2) of the shaft portion 59 of one of the conveying rolls 58A, and the pressing force (contact pressure of the pair of conveying rolls 58) applied to both end portions 59A of the shaft portion 59 of one of the conveying rolls 58A is reduced.

[0060] In this way, by raising and lowering the first guide section 61, it is possible to change the contact pressure of the pair of transport rolls 58 by selecting and using one or both of the two spring members 82, 84. Note that the pair of transport rolls 58 are configured such that only the contact pressure is changed, and the pair of transport rolls 58 are always maintained in contact due to the biasing force of the inner spring member 82, which does not separate from both end portions 59A of the shaft portion 59 of at least one of the transport rolls 58A.

[0061] 2, the outer surfaces of the lower end portions of a pair of support ribs 66 adjacent in the front-rear direction are connected by a flat connecting member 68 that extends in the front-rear direction with the up-down direction as its normal direction. A reinforcing member 69 in the form of a substantially rectangular flat plate is installed between the lower surface of the connecting member 68 and the upper surface of the first guide part 61 via a hinge part 69A whose rotation axis is in the left-right direction. Therefore, the first guide part 61 is configured to move rearward and rise at the same time.

[0062] Next, the operation of the transport device 60 according to the first embodiment configured as above will be described.

[0063] Generally, when the recording paper P is thick paper, it is better for the contact pressure of the pair of transport rolls 58 to be high, and it is better for the space between the lower surface of the first guide section 61 and the upper surface of the lower guide section 78 to be narrow. That is, while the thick paper is transported by the pair of transport rolls 58, the leading edge of the thick paper is brought into contact with the pair of alignment rolls 54 whose rotation is stopped, and a loop for skew correction is formed between the pair of transport rolls 58 and the pair of alignment rolls 54, and in the case of thick paper, it is better for the space for forming the loop to be narrow.

[0064] Furthermore, when the recording paper P is thick paper, it is preferable that the gap in the conveying path downstream of the pair of alignment rolls 54 is wide. If the gap in the conveying path downstream of the pair of alignment rolls 54 is narrow, the thick paper will come into contact with the continuous wall surfaces of the end portion 62A and the extension portion 62B of the second guide portion 62, and in some cases the thick paper will be forcibly bent while being conveyed, which may cause resistance to conveyance, misregistration, image shrinkage, or scratches.

[0065] Therefore, when the recording paper P is thick paper, as shown in FIG. 3, the first guide section 61 is in the lowered position and the second guide section 62 is in the retracted position. If the thick paper (recording paper P) is transported in this state, the parallelism of the thick paper is ensured, and the occurrence of wrinkles in the thick paper is suppressed or prevented, compared to when the contact pressure of the pair of transport rolls 58 on the recording paper P and the distance between the transport paths downstream of the pair of alignment rolls 54 are constant regardless of the type (basis weight) of the recording paper P. Furthermore, the thick paper is not forcibly bent during transport, so transport resistance and the like are not generated. This suppresses or prevents the occurrence of transport problems of the thick paper relative to the pair of alignment rolls 54 and the secondary transfer position T, and suppresses or prevents the occurrence of poor image quality due to such transport problems.

[0066] On the other hand, when the recording paper P is plain paper, which is thinner than cardboard, the contact pressure of the pair of transport rolls 58 does not need to be high, and it is preferable to have a wide space between the lower surface of the first guide portion 61 and the upper surface of the lower guide portion 78. In other words, while the plain paper is transported by the pair of transport rolls 58, the leading edge of the plain paper is brought into contact with the pair of alignment rolls 54, whose rotation is stopped, to form a loop for skew correction between the pair of transport rolls 58 and the pair of alignment rolls 54, and in the case of plain paper, it is preferable to have a wide space for forming the loop.

[0067] When the leading edge of a sheet of plain paper hits a pair of alignment rolls 54 that have stopped rotating, the plain paper may take on a convex upward position due to twisting or the like. If the loop formation space described above is narrow, the plain paper may be relatively pushed downward by the lower surface of the first guide section 61, and may be pinched from above and below between the upper surface of the lower guide section 78, which may cause further unnecessary twisting or the like to occur in the plain paper.

[0068] Furthermore, when the recording paper P is plain paper, it is preferable that the gap in the transport path downstream of the pair of alignment rolls 54 is narrow. If the gap in the transport path downstream of the pair of alignment rolls 54 is wide, it becomes difficult for the continuous wall surfaces of the end portion 62A and the extension portion 62B of the second guide portion 62 to come into contact with the plain paper, which may cause the position of the plain paper to become unstable and wrinkles to form in the plain paper. In other words, when using plain paper, it is necessary to actively bring the second guide portion 62 into contact with the paper and regulate its position until it reaches the secondary transfer position T.

[0069] Therefore, when the recording paper P is plain paper, the first guide portion 61 is in the raised position and the second guide portion 62 is in the extended position, as shown in Figure 4. The lower end portion 84A of the spring member 84 is separated from both ends 59A of the shaft portion 59 of one of the transport rolls 58A. In this way, when plain paper passes through the transport path, the loop-forming space described above is widened, the contact pressure between the pair of transport rolls 58 is adjusted to be weaker, and the gap in the transport path downstream of the pair of alignment rolls 54 is narrowed.

[0070] When plain paper (recording paper P) is transported in this state, poor transport of plain paper to the pair of alignment rolls 54 and secondary transfer position T is suppressed or prevented compared to when the contact pressure of the pair of transport rolls 58 on the recording paper P and the spacing of the transport path downstream of the pair of alignment rolls 54 are configured to be constant regardless of the type (basis weight) of the recording paper P, i.e., when the positions of the first guide section 61 and the second guide section 62 are the same as when thick paper is used and the contact pressure of the pair of transport rolls 58 is the same as when thick paper is used.

[0071] Specifically, even if plain paper assumes a convex upward position due to twisting or the like, the wide loop formation space prevents the paper from being relatively pushed downward by the underside of the first guide section 61. The stiffness of the plain paper as it is transported by the transport roll 58 eliminates the twisting and ensures the parallelism of the plain paper, thereby suppressing or preventing wrinkles from forming on the plain paper. The plain paper then actively contacts the continuous wall surfaces of the end section 62A and extension section 62B of the second guide section 62, and is transported to the secondary transfer position T while its position is regulated. This suppresses or prevents poor image quality due to poor transport.

[0072] Furthermore, when the recording paper P is plain paper, the contact pressure of the pair of conveying rolls 58 is adjusted to be reduced (to prevent excessive contact pressure), thereby suppressing wear on the conveying rolls 58 themselves and reducing the power consumption of the motor (not shown) that drives the conveying rolls 58.

[0073] Furthermore, since the loop formation space is expanded only when the recording paper P is thinner than cardboard (for example, regular paper), the size of the device body 11 of the image forming device 10 itself can be designed to match the loop formation space when using cardboard. This allows the image forming device 10 (device body 11) to be made smaller.

[0074] Furthermore, the first guide portion 61 and the second guide portion 62 are configured to move together to change their positions. That is, the first guide portion 61 and the second guide portion 62 are configured as a single unit. Therefore, compared to a configuration in which the first guide portion 61 and the second guide portion 62 move separately to change their positions, the number of parts can be reduced, and the configuration of the position variable mechanism 70 can be simplified.

[0075] Furthermore, the first guide section 61 and the second guide section 62 are configured to change their positions by rotating about an imaginary rotation axis S that is substantially coaxial with the rotation axis 54A of the pair of alignment rolls 54. Therefore, the positions of the first guide section 61 and the second guide section 62 can be changed with higher precision than when the first guide section 61 and the second guide section 62 are configured to change their positions by rotating about, for example, the downstream end section 61A of the first guide section 61 (see FIGS. 5 and 6).

[0076] Furthermore, the second guide section 62 has an extending section 62B at its end 62A facing the transport path of the recording paper P, the extending section 62B extending toward the pair of alignment rolls 54. Therefore, compared to when the second guide section 62 has an extending section (not shown) at its end 62A facing the transport path of the recording paper P that extends, for example, toward the opposite side from the pair of alignment rolls 54, the recording paper P (plain paper) is prevented from getting into the gap between the pair of alignment rolls 54 and the underside of the second guide section 62. This reduces or prevents poor transport of the recording paper P sent out by the pair of alignment rolls 54.

[0077] Furthermore, because the pressure variable mechanism 80 is made up of two spring members 82, 84, the configuration of the pressure variable mechanism is simplified compared to when the pressure variable mechanism is configured to change the pressure by directly pressing both end portions 59A of the shaft portion 59 with, for example, an electric actuator (not shown). Moreover, because each of the spring members 82, 84 is a thin wire simply bent into a roughly "U" shape, it is inexpensive, which is advantageous in terms of manufacturing costs.

[0078] Furthermore, each of the spring members 82, 84 is formed in a substantially U-shape and configured to press both end portions 59A of the shaft portion 59 of one of the transport rolls 58A toward the other of the transport rolls 58B. Therefore, it is easier to assemble each of the spring members 82, 84 compared to a configuration in which both end portions 59A of the shaft portion 59 of one of the transport rolls 58A are pressed toward the other of the transport rolls 58B by individual springs (coil springs, torsion springs, etc.).

[0079] Furthermore, if one transport roll 58A is configured to be separated from the other transport roll 58B, the force of transporting the recording paper P to the alignment roll 54 when rotation is stopped (paper leading edge propulsion force) will decrease, resulting in a decrease in skew correction capability. In contrast, the pair of transport rolls 58 in this embodiment always maintain a state of contact, so a decrease in skew correction capability is suppressed or prevented compared to a configuration in which one transport roll 58A is separated from the other transport roll 58B.

[0080] <<Second embodiment>> Next, a second embodiment will be described. Note that the same reference numerals are used to designate the same parts as those in the first embodiment, and detailed descriptions (including common functions) will be omitted as appropriate.

[0081] 5 and 6, the second embodiment differs from the first embodiment only in that the positions of the first guide portion 61 and the second guide portion 62 are changed by rotating around a downstream end portion (lower tip portion) 61A of the first guide portion 61. That is, the vicinity of the downstream end portion 61A of the first guide portion 61 is set as a virtual rotation axis S, and the positions of the first guide portion 61 and the second guide portion 62 are changed by rotating around this virtual rotation axis S.

[0082] With this configuration, it is possible to easily change the position of the second guide section 62 compared to a configuration in which the positions of the first guide section 61 and the second guide section 62 are changed by rotating about a virtual rotation axis that is substantially coaxial with the rotation axis 54A (see FIGS. 3 and 4) of one (the left side) of the pair of alignment rolls 54. In other words, it is possible to move the position of the second guide section 62 to the retracted position by a large amount with a small force.

[0083] The conveying device 60 according to this embodiment has been described above with reference to the drawings. However, the conveying device 60 according to this embodiment is not limited to the one shown in the drawings, and the design can be modified as appropriate within the scope of the present invention. For example, the recording paper P that is thinner than cardboard may be thin paper that is even thinner than regular paper. Furthermore, the first guide portion 61 and the second guide portion 62 need only be configured to move together and change position, and are not limited to being configured as a single unit.

[0084] Furthermore, the spring members 84 that are moved away from both end portions 59A of the shaft portion 59 of one of the transport rolls 58A by the first guide portion 61 may be arranged inside the spring members 82 that do not move away from both end portions 59A of the shaft portion 59 of the one of the transport rolls 58A. The first guide portion 61 may be configured to rise while moving forward.

[0085] Furthermore, the pressure variable mechanism 80, which changes the contact pressure of the pair of conveying rolls 58 in conjunction with the first guide section 61 whose position has been changed by the position variable mechanism 70, is not limited to being composed of two spring members 82, 84 formed in an approximately U-shape, but may also be composed of spring members or actuators (not shown) of other shapes, etc., as long as the contact pressure of the pair of conveying rolls 58 can be adjusted as described above.

[0086] (Addendum) (((1))) a pair of alignment rolls that transport the recording medium to the transfer unit at a predetermined timing; a pair of conveying rolls that are provided upstream of the pair of alignment rolls in a conveying direction of the recording medium and that convey the recording medium toward the pair of alignment rolls that are in a stopped state of rotation; a first guide section provided downstream of the pair of transport rolls in a transport direction of the recording medium, the first guide section guiding the recording medium to the pair of alignment rolls; a second guide section provided downstream of the pair of alignment rolls in a conveying direction of the recording medium and configured to guide the recording medium to the transfer section; a position variable mechanism that changes the positions of the first guide portion and the second guide portion depending on the type of the recording medium; a pressure variable mechanism that changes the contact pressure of the pair of conveying rolls in conjunction with the first guide portion whose position has been changed by the position variable mechanism; A conveying device comprising: (((2))) The conveying device according to (((1))), wherein the position variable mechanism changes the positions of the first guide portion and the second guide portion depending on the basis weight of the recording medium. (((3))) When the recording medium is paper that is thinner than cardboard, the position variable mechanism changes the position of the first guide unit so that a space between the pair of transport rolls on the downstream side in the transport direction of the recording medium is wider than when the thick paper is used, and changes the position of the second guide unit so that a gap between the pair of alignment rolls on the transport path on the downstream side in the transport direction of the recording medium is narrower than when the thick paper is used, The conveying device according to (((1))) or (((2))), wherein the pressure variable mechanism changes the contact pressure of the pair of conveying rolls to be lower than that for the thick paper. (((4))) The conveying device according to any one of (((1))) to (((3))), wherein the first guide portion and the second guide portion are configured to move together to change positions. (((5))) The conveying device described in (((4))) is configured so that the first guide section and the second guide section can change their positions by rotating around a rotation axis that is coaxial with the rotation axis of the pair of alignment rolls. (((6))) The conveying device described in (((4))) is configured so that the positions of the first guide section and the second guide section can be changed by rotating around the downstream end of the first guide section in the conveying direction of the recording medium. (((7))) The second guide portion has an extension portion at an end facing the transport path of the recording medium, the extension portion extending toward the pair of alignment rolls. (((8))) the pressure variable mechanism has two spring members with different biasing forces, A conveying device as described in any one of (((1))) to (((7))), wherein the contact pressure of the pair of conveying rolls can be changed by using one or both of the two spring members. (((9))) The two spring members are formed in a "U" shape and configured to press both ends of the shaft portion of one of the pair of transport rolls that protrude axially outward toward the other transport roll (((8))). (((10))) A conveying device according to any one of (((1))) to (((9))), a transfer unit that transfers a toner image onto the recording medium conveyed by the conveying device; a fixing device that fixes the toner image transferred by the transfer unit onto the recording medium; An image forming apparatus comprising:

[0087] According to the conveying device of (((1))), the contact pressure of the pair of conveying rolls provided upstream of the pair of alignment rolls in the conveying direction of the recording medium and the spacing of the conveying path downstream of the pair of alignment rolls in the conveying direction of the recording medium are configured to be constant regardless of the type of recording medium, and it is possible to suppress the occurrence of poor conveyance of the recording medium to the transfer section, compared to when these are configured to be constant regardless of the type of recording medium. According to the conveying device of (((2))), the contact pressure of the pair of conveying rolls against the recording medium and the spacing of the conveying path downstream of the pair of alignment rolls in the conveying direction of the recording medium can be configured to be constant regardless of the basis weight of the recording medium, thereby making it possible to suppress the occurrence of poor conveyance of the recording medium to the transfer section. According to the conveying device of (((3))), even when the recording medium is paper that is thinner than cardboard, it is possible to suppress the occurrence of poor conveyance of the paper to the transfer section compared to when the positions of the first guide section and the second guide section are the same as when the recording medium is cardboard and the contact pressure of the pair of conveying rolls is the same as when the recording medium is cardboard. According to the conveying device of (((4))), the number of parts can be reduced and the position-adjusting mechanism can be simplified compared to a configuration in which the first guide section and the second guide section move separately to change their positions. According to the conveying device of (((5))), the positions of the first guide section and the second guide section can be changed with greater precision than when the first guide section and the second guide section are configured so that their positions are changed by rotating around the downstream end of the first guide section in the conveying direction of the recording medium. According to the conveying device of (((6))), the position of the second guide section can be easily changed compared to when the first guide section and the second guide section are configured to change their positions by rotating around a rotation axis that is coaxial with the rotation axis of the pair of alignment rolls. According to the conveying device of (((7))), the occurrence of transport problems of the recording medium sent out by the pair of alignment rolls can be suppressed compared to when the second guide section has an extension section at the end facing the transport path of the recording medium that extends in the opposite direction from the pair of alignment rolls. According to the conveying device of (((8))), the configuration of the pressure variable mechanism can be simplified compared to when the pressure variable mechanism is configured with an electric actuator. According to the conveying device of (((9))), it is easier to assemble the spring members than when the device is configured such that both ends of the shaft portion of one of a pair of conveying rolls that protrude outward in the axial direction are pressed toward the other conveying roll by individual springs. According to the image forming device of (((10))), the occurrence of poor image quality due to poor transport of the recording medium to the transfer section can be suppressed compared to when the contact pressure of the pair of transport rolls, which are provided upstream of the pair of alignment rolls in the transport direction of the recording medium, on the recording medium and the spacing of the transport path downstream of the pair of alignment rolls in the transport direction of the recording medium are configured to be constant regardless of the type of recording medium. [Explanation of symbols]

[0088] 10 Image forming device 18 Fixing device 54 Alignment roll 58 Transport Roll 59 Shaft 60 Conveyor 61 1st Information Department 62 2nd Information Department 70 Variable position mechanism 80 Variable pressure mechanism 82 Spring member 84 Spring member P Recording paper (an example of a recording medium) S Virtual rotation axis (an example of a rotation axis) T Secondary transfer position (example of transfer section)

Claims

1. a pair of alignment rolls that transport the recording medium to the transfer unit at a predetermined timing; a pair of conveying rolls that are provided upstream of the pair of alignment rolls in a conveying direction of the recording medium and that convey the recording medium toward the pair of alignment rolls that are in a stopped state of rotation; a first guide section provided downstream of the pair of transport rolls in a transport direction of the recording medium, the first guide section guiding the recording medium to the pair of alignment rolls; a second guide section provided downstream of the pair of alignment rolls in a conveying direction of the recording medium and configured to guide the recording medium to the transfer section; a position variable mechanism for changing the positions of the first guide portion and the second guide portion according to the type of the recording medium; a pressure variable mechanism that changes the contact pressure of the pair of transport rolls in conjunction with the first guide portion whose position has been changed by the position variable mechanism; A conveying device comprising:

2. The conveying device according to claim 1 , wherein the position variable mechanism changes the positions of the first guide portion and the second guide portion depending on the basis weight of the recording medium.

3. When the recording medium is paper that is thinner than cardboard, the position variable mechanism changes the position of the first guide unit so that a space between the pair of transport rolls on the downstream side in the transport direction of the recording medium is wider than when the thick paper is used, and changes the position of the second guide unit so that a gap between the pair of alignment rolls on the transport path on the downstream side in the transport direction of the recording medium is narrower than when the thick paper is used, The conveying device according to claim 1 , wherein the pressure varying mechanism changes the contact pressure between the pair of conveying rolls to be lower than that for the thick paper.

4. The conveying device according to claim 1 , wherein the first guide portion and the second guide portion are configured to move together to change positions.

5. The conveying device according to claim 4, wherein the first guide portion and the second guide portion are configured to change their positions by rotating around a rotation axis that is coaxial with the rotation axis of the pair of alignment rolls.

6. The conveying device according to claim 4 , wherein the first guide portion and the second guide portion are configured to change their positions by rotating around the downstream end of the first guide portion in the conveying direction of the recording medium.

7. The conveying device according to claim 1 , wherein the second guide portion has an extension portion that extends toward the pair of alignment rolls at an end portion facing the conveying path of the recording medium.

8. the pressure variable mechanism has two spring members with different biasing forces, 2. The conveying device according to claim 1, wherein the contact pressure between the pair of conveying rolls is changeable by using one or both of the two spring members.

9. The conveying device described in claim 8, wherein the two spring members are formed in a "U" shape and are configured to press both ends of the shaft portion of one of the pair of conveying rolls that protrude axially outward toward the other conveying roll.

10. A conveying device according to any one of claims 1 to 9; a transfer unit that transfers a toner image onto the recording medium conveyed by the conveying device; a fixing device that fixes the toner image transferred by the transfer unit onto the recording medium; An image forming apparatus comprising:

Images