JP5129020B2 - Sheet conveying apparatus and image forming apparatus - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying apparatus that abuts a fed sheet and corrects skew by forming a deflection on the sheet. For example, a copier, printer, facsimile apparatus, and finisher adopting an electrophotographic system or an inkjet system The present invention relates to a sheet conveying apparatus applied to an image forming apparatus such as a double-sided reverse conveying apparatus.

  In a conveying apparatus that conveys a sheet, when removing the skew or skew of the sheet and feeding the sheet at an appropriate timing, generally, a pair of paper feed rollers, that is, a registration roller pair and an upstream side thereof in the conveyance path And a pair of conveying rollers for conveying the sheet.

  Then, the leading edge of the sheet passing through the conveying roller pair advances to the nip position of the registration roller pair that has stopped rotating, and after forming a predetermined loop (deflection), the rotation of the conveying roller stops, A method is adopted in which the leading edge of the sheet-like medium is in a state parallel to the axis of the registration roller pair by the restoring force of the loop, and is skew-corrected and fed at a predetermined timing.

  By the way, for example, a collision sound is generated due to a collision force when the sheet tip collides with the registration roller pair, but a device in which silent performance is regarded as important, for example, a copier, a printer, and a facsimile apparatus adopting an electrophotographic method or an inkjet method. In the case of a finisher, a double-sided reversing conveyance device, etc., it becomes a problem to reduce the collision sound, in other words, to reduce a collision force that is a cause of the collision noise.

In Patent Document 1, “in order to suppress the impact sound caused when the conveyed paper directly collides with the registration rollers, the pair of registration rollers are provided with a large-diameter portion made of an elastic body in at least two locations in the axial direction of the roller pair. Alternatively, the registration roller may be formed so as to make a round, and an elastic body may be fitted into the recess to constitute the large diameter portion. First, the fed paper is brought into contact with the elastic body to suppress the impact sound. Thereafter, the sheet comes into contact with the registration roller. It is said.
Japanese Patent Laid-Open No. 9-30688

  However, the stiffness of the sheet (the stiffness of the sheet. JIS has a test method called the Clark method) due to the type of sheet being transported, the thickness, the difference between the vertical and horizontal eyes, or the ambient environment of temperature and humidity. In particular, the sheet thickness is thin and the direction perpendicular to the feeding direction is the opposite of that in a high-temperature and high-humidity environment, and the sheet thickness is thick and parallel to the feeding direction. The stiffness of the sheet is completely different from that in the low temperature and low humidity environment. The former is a case where the rigidity is low and the latter is high. However, when they are rushed into the registration roller pair at a uniform conveying speed, the contact portion of the sheet is caused by the collision with the local elastic body of the present invention in the former combination. In the latter combination, the local elastic body is instantaneously compressed and pushed to the nip position of the registration roller pair at once, thereby reducing the effect of reducing the collision force. Occurs.

  The present invention has been made in view of the above-described problems of the prior art, and appropriately reduces the collision force when various sheets having different stiffness collide with the registration roller. An object of the present invention is to provide a sheet conveying apparatus capable of reducing a sound and correcting a skew and feeding a sheet at an appropriate timing.

In order to achieve the above object, the invention according to claim 1 is a sheet conveying apparatus comprising a pair of registration rollers that abuts a fed sheet and corrects skew by forming a deflection on the sheet. An abutting member for reducing the collision force of the sheet to the registration roller is provided in the vicinity of the nip of the roller pair. The abutting member comes in contact with the leading end of the sheet on the upstream side of the conveying path from the abutting member and swings according to the rigidity of the sheet. A swinging member that moves is provided, and the contact member protrudes onto the sheet conveyance path when the leading end of the sheet contacts the swinging member.

  According to a second aspect of the present invention, in the sheet conveying apparatus according to the first aspect, the amount of protrusion of the abutting member on the sheet conveying path varies according to a contact force with which the sheet contacts the swinging member. It is characterized by this.

  According to a third aspect of the present invention, in the sheet conveying apparatus according to the first aspect, the curved conveying path is curved, the swinging member is disposed in the curved conveying path, and the swinging member swings the swinging member. The sheet is projected onto the sheet conveyance path by power.

  According to a fourth aspect of the present invention, in the sheet conveying apparatus according to any one of the first to third aspects, a plurality of portions of the abutting member that are in contact with the front end of the sheet are arranged in a direction perpendicular to the sheet conveying direction. It is characterized by being divided.

  According to a fifth aspect of the present invention, in the sheet conveying apparatus according to the fourth aspect, a plurality of the swinging members are provided in a direction orthogonal to the sheet conveying direction, and each swings independently. To do.

The invention according to claim 6 is the sheet conveying apparatus according to any one of claims 1 to 5, wherein the swinging member and the contact member are separate and each has a swinging fulcrum, The swing member is in contact with the sheet on the downstream side in the sheet conveyance direction from the swing support point of the swing member .

  According to a seventh aspect of the present invention, in the sheet conveying apparatus according to any one of the first to sixth aspects, at least one of the registration roller pair is divided into a plurality of parts in a direction perpendicular to the sheet conveying direction, The contact member has a hollow cylindrical shape, and is coaxially disposed between the plurality of divided registration rollers. When the leading edge of the sheet comes into contact with the swinging member, the contact member is decentered in a direction opposite to the sheet conveyance direction. Thus, the sheet is projected onto the sheet conveyance path.

  According to an eighth aspect of the present invention, there is provided the sheet conveying apparatus according to any one of the first to seventh aspects, and an image forming unit that forms an image on a sheet fed from the sheet conveying apparatus. It is what.

  According to the present invention, it is possible to reduce the collision force generated when the leading edge of the sheet collides with the registration roller pair.

  Hereinafter, embodiments of a sheet conveying apparatus according to the present invention will be described with reference to the drawings.

[First Embodiment]
A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall view of an image forming apparatus 100 according to the present invention, FIG. 2 is a diagram illustrating a state in which a highly rigid sheet passes through a sheet conveying unit 20 according to the first embodiment of the present invention, and FIG. FIG. 4 is a perspective view of the sheet conveying unit 20 according to the first embodiment of the present invention, and FIG. 4 is a diagram illustrating a state in which a low-rigidity sheet passes through the sheet conveying unit 20 according to the first embodiment.

  FIG. 1 is an overall view of an image forming apparatus 100 of the present invention. The image forming apparatus 100 includes a sheet feeding unit 10 that feeds sheets, a sheet conveyance unit 20 that conveys sheets fed from the sheet feeding unit 10, an image forming unit 60 that performs image formation, and a sheet conveyance unit 20. The image forming unit 60 includes a transfer unit 70 that transfers an image formed by the image forming unit 60 to the fed sheet, and a fixing unit 90 that fixes the image transferred to the sheet by the transfer unit 70 on the sheet.

  The sheet feeding unit 10 stores and stacks sheets, a pickup roller 13 that separates the uppermost sheet from the stacked sheet bundle 12 by friction conveying force, and reliably separates and conveys one sheet. And a pair of paper feed rollers 14. The pair of sheet feed rollers 14 includes a sheet feed roller 15 that rotates in a direction in which the sheet is conveyed, and a sheet feed reverse roller 16 that rotates with a predetermined torque in a direction opposite to the rotation of the feed roller.

  The sheet conveying unit 20 as a sheet conveying device reduces the collision force that the sheet collides with the registration roller nip region 55 and the conveying roller pair 23 that conveys the sheet fed from the sheet feeding unit 10 to the registration unit 21. Collision force reduction means 22 and registration means 21 that feeds the sheet at a predetermined timing after the sheet is abutted and stopped once to perform skew correction. The conveyance roller pair 23 includes a conveyance driving roller 24 driven by a driving source (not shown) and a conveyance driven roller 25 to which a rotational force is applied by the conveyance driving roller 24.

  The collision force reduction means 22 is a swing arm 31 that swings when contacted with a fed sheet, and a contact member that contacts the tip of the sheet and reduces the collision force against the registration roller. A contact 40 and a curved curved conveyance path 30 are provided. The swing arm 31 as a swing member includes a swing arm rotation shaft portion 33, a swing arm rotation fulcrum portion 34, a swing arm upstream side portion 35, a swing arm apex portion 36, and a swing arm downstream. A side portion 37, a swing arm tip portion 38, and a swing arm spring 39 are provided. The contact 40 as a contact member includes a contact shaft portion 42, a contact rotation fulcrum portion 43, a contact contact portion 44, a contact lever portion 45, and a contact spring 46. The curved curved conveyance path 30 includes an upper guide plate 26 and a lower guide plate 29. The upper guide plate 26 includes an upper guide plate upstream portion 27, an upper guide plate downstream portion 28, a swing arm fulcrum support portion 32, and a contact fulcrum support portion 41.

  The registration unit 21 includes a registration roller pair 48 that abuts a sheet and temporarily stops and corrects skew feeding, a front registration sensor 56 that detects the leading edge of the sheet, and a rear registration sensor 57. The registration roller pair 48 includes a registration driving roller 49 driven by a driving source (not shown) and a registration driven roller 52 to which a rotational force is applied by the registration driving roller 49. The front registration sensor 56 is installed upstream of the registration roller nip area 55 in the conveyance direction, and the rear registration sensor 57 is installed downstream of the registration roller nip area 55 in the conveyance direction. As a result, it is possible to accurately detect the sub-scanning position at which the leading edge of the sheet stops on the upstream side of the registration roller nip region 55, and the sheet leading edge passage timing (position) after registration, which differ for each sheet thickness.

  The conveyance drive roller 24 is preferably arranged on the opposite side of the swing arm 31 with the conveyance roller front conveyance path 58 (sheet conveyance path) indicated by a two-dot chain line as shown in FIG. For example, when a thick sheet has been fed, the linear speed of the conveyance driving roller 24 is slightly higher than the linear speed of the conveyance driven roller 25, so that the leading edge of the sheet advances obliquely forward on the conveyance driven roller 25 side. Therefore, compared to the case where the conveyance drive roller 24 and the swing arm 31 are arranged on the same side with respect to the sheet conveyance path, the conveyance drive roller 24 and the swing arm 31 are arranged on the opposite side with respect to the sheet conveyance path. This is because the sheet is sent out toward the swing arm 31 and the contact is facilitated.

  The image forming unit 60 includes an image forming unit Y61, an image forming unit M62, an image forming unit C63, and an image forming unit BK64 that form yellow, magenta, cyan, and black colors on the intermediate transfer belt 75. Since each image forming unit has the same configuration except for the toner color, the image forming unit Y61 will be described as an example. The image forming unit Y61 includes a photosensitive drum 65 carrying a yellow toner image, a charging unit 68 for charging the surface of the photosensitive drum 65, and a laser beam for forming a latent image on the uniformly charged surface. Exposure means 67 for irradiating, a developing means 68 for forming a toner image on a latent image on the surface of the photosensitive drum, and a cleaning means 69 for recovering toner remaining without being transferred to the surface of the photosensitive drum. .

  The transfer unit 70 includes an intermediate transfer belt 75 that superimposes toner images formed by the image forming unit 60, and a primary transfer unit Y71, a primary transfer unit M72, and 1 that transfer toner images of each color onto the intermediate transfer belt 75. Next transfer portion C73, primary transfer portion BK74, transfer roller 79 that transfers the toner image superimposed on intermediate transfer belt 75 to the sheet, and opposing roller 80 that is disposed opposite to the transfer roller and forms a nip. Prepare. The intermediate transfer belt 75 includes a belt driving roller 76 driven by a driving source (not shown), a belt driven roller 77 to which a rotational force is applied by the intermediate transfer belt 75, and a belt stretching roller that applies a constant load to the intermediate transfer belt 75. Rotate 78 with constant tension.

  The fixing unit 90 includes a fixing roller pair 91, and the fixing roller pair 91 includes a heating roller 92 including a heat source such as a halogen lamp, and a pressure roller 93 pressed toward the heating roller 92.

  The uppermost sheet of the sheet bundle 12 stacked on the sheet cassette 11 is separated from the sheet bundle 12 by the friction conveying force of the pickup roller 13, and a sheet feed roller 15 that rotates in the sheet conveying direction, and a sheet feed roller The sheet is reliably separated and conveyed into one sheet by a paper feed reverse roller 16 that rotates at a predetermined torque in a direction opposite to the rotation of 15, and further conveyed by a pair of conveyance rollers 23.

  When the leading edge of the sheet passes through the conveyance driving roller 24 and the conveyance driven roller 25, the curved conveyance path 30 is conveyed while being regulated by the upper guide plate 26 and the lower guide plate 29, and the leading edge of the sheet is the swing arm 31. To touch. The swing arm 31 is attached to the swing arm fulcrum support portion 32, and uses the swing arm rotation fulcrum portion 34 as a swing fulcrum, and contacts the front end of the seat at the swing arm upstream side portion 35. The swing arm 31 applies a predetermined pressure to the seat by the repulsive force of the swing arm spring 39.

  Here, when the stiffness of the seat is relatively weak, since the force for pushing the swing arm 31 is weak, the repulsive force by the swing arm spring 39 is superior and the swing arm 31 does not swing. Therefore, the leading edge of the sheet is conveyed along the normal position of the swing arm 31.

  Then, by passing through the previous registration sensor 56, the arrival time to the registration roller nip area 55 of the registration roller pair 48 in a state where the rotation is stopped is calculated. After the leading edge of the sheet reaches the registration roller nip, the sheet is bent (loop) by performing a control to rotate and stop the conveyance driving roller 24 for a predetermined time, and by the restoring force to return to the plane of the sheet itself, Skew correction is performed in order to achieve a posture in which the leading edge of the sheet comes into contact with the registration roller nip evenly.

  By the way, when the seat has a relatively high rigidity, the swinging arm 31 swings over the repulsive force of the swinging arm spring 39 because the force that pushes the swinging arm 31 is strong. Accordingly, the leading edge of the sheet is conveyed along the upper guide plate 26. At this time, the swing arm tip portion 38 contacts the contact lever portion 45 and pushes the contact lever away. As a result, the contact 40 swings around the contact fulcrum support portion 41 as a swing fulcrum and protrudes onto the sheet conveyance path.

  The leading edge of the sheet conveyed along the upper guide plate 26 abuts against the contact point contact portion 44 before colliding with the registration roller pair 48, thereby reducing the collision force. Thereafter, the leading edge of the sheet reaches the registration roller nip region 55, and skew correction is performed in the same manner as in the case of a sheet having low rigidity.

  Immediately before the skew correction is performed, for example, in the case of a so-called four-tandem color image forming apparatus, a color toner image is converted into an image forming unit Y61, an image forming unit M62, an image forming unit C63, and an image forming unit. An image is formed by BK64 and is primarily transferred to the intermediate transfer belt 75. The intermediate transfer belt 75 starts to be conveyed (sub-scanning) by an inscribed belt driving roller 76 and is continuously stretched by a belt driven roller 77, a counter roller 80, a belt stretching roller 78, and the like, so that toner images are sequentially transferred. Is done. After that, the toner image is synchronized with the leading edge of the toner image and the leading edge of the sheet conveyed from the registration roller pair 48 in a region where the opposing roller 80 and the transfer roller 79 are nipped. Secondary transferred onto the surface. Then, heat fixing is performed by the fixing roller pair 91 on the downstream side in the sheet conveying direction, and the sheet is discharged outside the apparatus.

  FIG. 2 is a diagram illustrating a state in which a highly rigid sheet passes through the sheet conveying unit 20 according to the first embodiment of the present invention. The same reference numerals as those used in FIG. 1 are used.

  In FIG. 2A, the leading end portion of the highly rigid sheet conveyed from the conveying roller pair 23 swings along the upper guide plate upstream side portion 27 by the restoring force of the sheet to be changed from the curved surface to the flat surface. The state which contacted the arm upstream side part 35 is shown. The shape from the leading edge of the sheet to the conveying roller pair 23 on the upstream side is slightly straight because the rigidity of the sheet is high and thus the restoring force described above is strong and difficult to bend.

  In FIG. 2B, the leading end of the sheet reaches the swing arm apex portion 36. At this time, the swing arm spring 39 is moved to the swing arm 31 drawn by a dotted line by the restoring force of the highly rigid sheet. A force for compressing is applied, and the rocking arm rotating shaft 33 is swung in the clockwise direction to the state depicted by the solid line with the rocking center as the rocking center. As a result of the swing, the swing arm tip portion 38 swings the contact lever portion 45 counterclockwise about the contact rotation fulcrum 43, and the contact contact portion 44, which is an integral structure, is also contacted with the contact rotation fulcrum portion. It swings counterclockwise around 43 and protrudes so as to slightly block the sheet conveyance path.

  FIG. 2C shows a state in which the leading edge of the sheet has reached the detection position of the front registration sensor 56, and the sheet is conveyed along the upper guide plate downstream side portion 28.

  FIG. 2 (d) shows a state in which the front end of the sheet is in contact with the contact point 44 that has already swung counterclockwise. It shows a place that is losing and curving.

  FIG. 2E shows a state in which the leading edge of the sheet has reached the nip area 55 of the stopped pair of registration rollers 48. At this time, according to the timing when the front registration sensor 56 described in FIG. 2C detects the leading edge of the sheet, the rotation of the conveying roller pair 23 is stopped after a predetermined time has elapsed, and a predetermined loop is formed, thereby performing the skew. Correction is performed.

  FIG. 3 is a diagram illustrating a state in which a low-rigidity sheet passes through the sheet conveying unit 20 according to the first embodiment of the present invention. The same reference numerals as those used in FIG. 1 are used.

  In FIG. 3A, the leading end of the sheet having low rigidity conveyed from the conveying roller pair 23 is along the upper guide plate upstream side 27 by the restoring force to make the sheet flat, and the swing arm The state at the moment of contact with the upstream side portion 35 is shown. The shape from the leading end of the sheet to the conveying roller pair 23 on the upstream side is low in rigidity, so that the restoring force described above is weak and easily bent, so that it follows the upper guide plate upstream side portion 27.

  In FIG. 3B, the leading end of the sheet reaches the swing arm apex portion 36. At this time, the swing arm 31 drawn by a solid line has a low repulsive force of the swing arm spring 39. It does not rock to overcome the restoring force. Therefore, the swing arm tip portion 38 does not swing the contact lever portion 45, and the contact contact portion 44 having an integral structure does not protrude onto the sheet conveyance path.

  FIG. 3C shows a state where the leading edge of the sheet has reached the detection position of the front registration sensor 56, and the sheet is conveyed along the lower guide plate 29 by the restriction by the swing arm apex portion 36. .

  FIG. 3D shows a state in which the leading edge of the sheet passes through the vicinity of the contact point 44 where the sheet is retracted to a position that does not block the sheet conveyance path.

  FIG. 3E shows a state in which the leading edge of the sheet has reached the nip area 55 of the stopped pair of registration rollers 48. At this time, according to the timing at which the front registration sensor 56 described in FIG. 3C detects the leading edge of the sheet, the rotation of the conveying roller pair 23 is stopped after a predetermined time has elapsed, and a predetermined loop is formed, thereby performing the skew. Correction is performed.

  In the above description, the sheet having high rigidity and the sheet having low rigidity are described. However, when plain paper having medium rigidity is transported, the swing arm 31 swings by an amount corresponding to the sheet rigidity. The moving arm tip portion 38 swings the contact lever portion 45 by that amount and causes the contact point contact portion 44 to protrude by an amount suitable for the rigidity of the sheet.

  For the swing of the contact 40, a drive source such as an actuator may be provided separately. In that case, a sensor for detecting the displacement amount of the swing arm is provided, and the detection result is converted into the drive amount of the actuator. Thus, the effects of the present invention can be achieved.

  A necessary characteristic of the material of the contact point contact portion 44 is that the shape of the outer periphery is elastically deformed according to an external force. For example, it may be formed of a resin film, elastic resin, vulcanized rubber, elastomer, metal foil or the like. Moreover, you may comprise with the fiber by inorganic materials, such as a metal fiber and a carbon fiber, and the fiber by organic materials, such as a cellulose fiber.

  FIG. 4 is a perspective view of the sheet conveying apparatus 20 according to the first embodiment of the present invention. As shown in FIG. 4, in this embodiment, left and right contacts 40L and R as the contact 40 and left and right swing arms 31L and R as the swing arm 31 are provided in a direction perpendicular to the sheet conveying direction. Yes, the left and right sides can swing independently. Hereinafter, the contact 40 and the swing arm 31 provided on the left and right are expressed as a contact 40L · R and a swing arm 31L · R for convenience. Similarly, the openings 59 provided on the left and right are also expressed as openings 59L and R.

  The swing arms 31L and 31R are installed so as to protrude from the openings 59L and R provided in the upper guide plate 26 toward the curved conveyance path 30 shown in FIG. The left and right swing arm springs 39L and R fixed to a member (not shown) maintain the left and right swing arms 31L and R in the normal position by their repulsive forces.

  The left and right contact lever portions 45L and R are maintained at normal positions by left and right contact springs 46L and R that are similarly fixed to members (not shown), and are configured integrally with the contact lever portions 45L and R, respectively. Contactor contact portions 44L and R are maintained at a position retracted from the sheet conveyance path.

  When the sheet is conveyed from the sheet feeding unit 10 shown in FIG. 1, the conveying roller pair 23 sends the sheet downstream in the sheet conveying direction. When the left and right swing arms 31L and R come into contact with the sheet leading ends, the swing arms 31L and R swing according to the rigidity of the seat, respectively, and the swing arm tip portions 38L and R swing the swing left and right. The contact lever portions 45L and R swing and the left and right contact portions 44L and R swing to project onto the sheet conveyance path.

  The conveyed sheet is brought into contact with the left and right contact portions 44L and R, so that the collision force against the stopped pair of registration rollers 48 is reduced.

  At this time, since the swing arms 31L and R and the contacts 40L and R swing independently on the left and right, even if the sheet is conveyed in a skewed state, the sheet can be moved in a timely manner. Abutting with the contact 40L or the contact 40R, the skew can be reduced. Further, since the contact points 44L and R are respectively in a direction perpendicular to the sheet conveying direction, the contact point with the sheet becomes two places, and local stress is applied to the sheet as compared with the case where contact is made at one place. It can be prevented from occurring. Furthermore, since a plurality of contacts 40 and swing arms 31 are provided, it is possible to enhance the effect of preventing the generation of local stress generated in the above-described sheet.

  In this way, the sheet having reached the registration roller nip area 55 with reduced collision force forms a predetermined deflection and corrects skew feeding, and then is sent to the transfer unit 70 by the rotation of the registration roller pair 48.

  Further, it is desirable that the plurality of contacts 40 and the swing arm 31 are provided symmetrically from the center in the direction orthogonal to the sheet conveying direction so that at least one contact point 44 is at the minimum sheet width. .

  In addition, you may comprise so that the contactor contact part 44 may be provided with two or more with respect to each of the some rocking | swiveling arm 31, and the number ratio does not need to be 1: 1.

  A modification according to the first embodiment of the present invention will be described below with reference to the drawings. FIG. 5 is a perspective view of a modified sheet conveying unit 20 according to the first embodiment of the present invention, and FIG. 6 is a front view thereof. The same reference numerals are used for the same components as those in FIG.

  As shown in FIG. 5, in this modification, the contact point contact portion 44 is divided into two in a direction perpendicular to the sheet conveyance direction. Hereinafter, the contactor contact portion 44 divided into two parts is expressed as contactor contact portions 44L and R for convenience.

  The swing arm 31 is installed so as to protrude from the opening 59 provided in the upper guide plate 26 toward the curved conveyance path 30 shown in FIG. The swing arm spring 39 fixed to a member (not shown) maintains the swing arm 31 in the normal position by the repulsive force.

  Similarly, the contact lever portion 45 is maintained in a normal position by a contact spring 46 fixed to a member (not shown), and the left and right contact contact portions 44L and R configured integrally with the contact lever portion 45 are seats. It is maintained at a position retracted from the transport path.

  When the sheet is conveyed from the sheet feeding unit 10 shown in FIG. 1, the conveying roller pair 23 sends the sheet downstream in the sheet conveying direction. When the swing arm 31 comes into contact with the leading end of the sheet, the swing arm 31 swings according to the stiffness of the sheet, and the swing arm tip portion 38 transmits the swing to the contact lever portion 45. The left and right contact contact portions 44L and R swing and project onto the sheet conveyance path.

  The conveyed sheet is brought into contact with the left and right contact portions 44L and R, so that the collision force against the stopped pair of registration rollers 48 is reduced.

  At this time, since the contact points 44L and R are respectively in a direction orthogonal to the sheet conveyance direction, there are two contact points with the sheet, and local stress is applied to the sheet as compared with the case where the contact is made at one point. Can be prevented. Further, when a plurality of contact point contact portions 44 are provided, it is possible to enhance the effect of preventing the occurrence of the above-described local stress.

  In this way, the sheet having reached the registration roller nip area 55 with reduced collision force forms a predetermined deflection and corrects skew feeding, and then is sent to the transfer unit 70 by the rotation of the registration roller pair 48.

  FIG. 6 is a front view of a modification according to the first embodiment of the present invention. As shown in FIG. 6, when a plurality of contact points 44 are provided, C.I. L. It is desirable to provide them symmetrically from (center line) so that at least one contact point 44 is at the minimum sheet width.

[Second Embodiment]
A second embodiment of the present invention will be described below with reference to the drawings. FIG. 7 is a perspective view of a sheet conveying unit 20A according to the second embodiment of the present invention, and FIG. 8 is a front view thereof. 9 and 10 are enlarged views of the vicinity of the registration roller pair 48 in FIG. The same reference numerals are used for the same components as those in FIGS. 1 and 5.

  As shown in FIG. 7, in this embodiment, the contact 40 as a contact member includes an intermediate lever shaft portion 111, an intermediate lever rotation fulcrum portion 112, intermediate lever arch portions 113 </ b> L and R, and an intermediate lever portion 116. And annular contactors 117L and R disposed on the outer periphery of the resist driven roller small diameter portion 53 without covering the resist driven rollers 52 on both sides, and an annular contact spring 119. The intermediate lever arch portions 113L and R are in contact with the annular contacts 117L and R at two points of the first arch contact portions 114L and R and the second arch contact portions 115L and R, and the annular contacts 117L and R are in annular contact. The child contact portions 118L and R abut against the sheet.

  The swing arm 31 is installed so as to protrude from the opening 59 provided in the upper guide plate 26 toward the curved conveyance path 30 shown in FIG. The swing arm spring 39 fixed to a member (not shown) maintains the swing arm 31 in the normal position by the repulsive force.

  The intermediate lever lever 116 is also maintained at a normal position by an annular contact spring 119 fixed to a member (not shown), and left and right intermediate lever arch portions 113L and R configured integrally with the intermediate lever lever 116 are also included. Maintained in normal position. The intermediate lever arch portions 113L and R are in contact with the outer circumference of the annular contactor 117L and R at two points of the first arch contact portions 114L and R and the second arch contact portions 115L and R. The annular contacts 117L and R are positioned by the three points of the inner contact between the two points and the resist driven roller small-diameter portion 53, and are maintained at the position retracted from the sheet conveyance path.

  In FIG. 7, when a sheet is conveyed from the sheet feeding unit 10 shown in FIG. 1, the conveying roller pair 23 sends the sheet downstream in the sheet conveying direction. When the swing arm 31 comes into contact with the leading end of the sheet, the swing arm 31 swings according to the stiffness of the sheet, and the swing arm tip portion 38 transmits the swing to the intermediate lever lever portion 116. The part 116 swings. As a result, the intermediate lever arch portions 113L and R swing around the intermediate lever rotation fulcrum portion 112, and the annular contacts 117L and R protrude onto the sheet conveyance path.

  The conveyed sheet abuts on the annular contactor 117L • R and the annular contactor contact portion 118L • R, so that the collision force of the stopped registration roller pair 48 against the nip region 55 is reduced.

  At this time, since the annular contacts 117L and R are in a direction orthogonal to the sheet conveying direction, the contact point with the sheet becomes two places, and the local stress is applied to the sheet more than when the contact is made at one place. It can be prevented from occurring. In addition, when a plurality of annular contacts 117L and R are provided, it is possible to enhance the effect of preventing local stress generated in the above-described sheet.

  Furthermore, since the annular contacts 117L and R can be brought into contact with the sheet on the surface and the contact time can be extended, the effect of reducing the collision force is enhanced. Since the contact between the annular contact point 118L / R and the sheet changes, there is an effect of preventing wear and damage to a specific part rather than contact at a specific point, and an effect of improving durability can be obtained.

  In this way, the sheet having the collision force reduced and reaching the nip region 55 of the registration roller pair 48 forms a predetermined deflection and corrects the skew feeding, and then is sent to the transfer unit 70 by the rotation of the registration roller pair 48.

  FIG. 8 is a front view of the sheet conveying unit 20A according to the second embodiment of the present invention. In the case where a plurality of annular contacts 117 are provided, C.I. L. It is desirable to provide them symmetrically from (center line) so that at least one annular contact 117 is at the minimum sheet width.

  Here, the operation of the annular contacts 117L and R protruding onto the sheet conveyance path will be described with reference to FIGS. 9 to 12 are cross-sectional views, so that reference numerals are abbreviated as LR.

  FIG. 9 is an enlarged view of the annular contact 117 maintained in a normal state and the vicinity thereof. The second arch contact portion 115 draws a perpendicular line from the center of the registration driven roller shaft portion 54 with respect to a straight line connecting the center of the registration driving roller shaft portion 51 and the center of the registration driven roller shaft portion 54, and the intermediate lever arch portion 113. And at the downstream side in the sheet conveying direction. Further, the inner contact between the annular contact 117 and the resist driven roller small diameter portion 53 is a point where a circle passing through the second arch contact portion 115 contacts an outer circumference circle of the resist driven roller small diameter portion 53.

  At this time, the annular contact 117 is positioned by the three points of the first arch contact 114, the second arch contact 115, and the inner contact, and is maintained at a position retracted from the sheet conveyance path.

  FIG. 10 is an enlarged view of the annular contact 117 and its surroundings in a state of protruding onto the sheet conveyance path. Since the intermediate lever arch portion 113 has an arc shape centered on the intermediate lever rotation fulcrum portion 112 in the second arch contact portion 115, even if the intermediate lever arch portion 113 swings around the intermediate lever rotation fulcrum portion 112. The position of the second arch contact portion 115 does not change. For this reason, the annular contact 117 is restricted from being eccentric in the sheet conveyance direction.

  At this time, the annular contact 117 is sandwiched between the first arch contact portion 114 and the second arch contact portion 115 from the upstream side and the downstream side in the sheet conveyance direction, and is pressed by the intermediate lever arch portion 113, so that the sheet conveyance is performed. Since the eccentricity in the direction and in the direction away from the sheet conveyance path is restricted, the registration driven roller 52 protrudes from the conveyance path. A portion of the annular contact 117 protruding from the registration driven roller 52 on the conveyance path is an annular contact point 118.

  The annular contact point 118 may be protruded onto the sheet conveyance path without restricting the eccentricity by the second arch contact point 115. This is because it is sufficient that the annular contactor 117 has at least a portion protruding from the registration driven roller 52 to the upstream side in the sheet conveying direction.

  FIG. 11 is a diagram illustrating a state in which a highly rigid sheet passes through the sheet conveying unit 20A according to the second embodiment of the present invention. The same reference numerals are used for the same components as those in FIG.

  In FIG. 11A, the leading end portion of the highly rigid sheet conveyed from the conveying roller pair 23 is positioned along the upper guide plate upstream side 27 by the restoring force of the sheet to become a plane, and the upstream side of the swing arm. The state which contacted the side part 35 is shown. The shape from the leading edge of the sheet to the conveying roller pair 23 on the upstream side is slightly straight because the rigidity of the sheet is high and thus the restoring force described above is strong and difficult to bend.

  In FIG. 11 (b), the leading end of the sheet reaches the swing arm apex portion 36. At that time, the swing arm spring 39 is moved to the swing arm 31 drawn by a dotted line by the restoring force of the highly rigid sheet. A force for compressing is applied, and swings clockwise to a state depicted by a solid line with the swing arm rotation shaft portion 33 as the swing center. As a result of the swing, the swing arm tip 38 swings the intermediate lever lever 116 counterclockwise about the intermediate lever rotation fulcrum 112, and the intermediate lever arch 113 formed integrally with the intermediate lever lever 116. Swings about the intermediate lever rotation fulcrum 112. As a result, the first arch contact portion 114 approaches the axis of the registration driven roller 52, and the annular contact 117 is pressed by the intermediate lever arch portion 113.

  By the way, the annular contact 117 is sandwiched between the second arch contact portion 115 and the resist driven roller small diameter portion 53 as described above. However, when the first arch contact portion 114 approaches the axial center of the resist driven roller 52, the hollow portion of the annular contactor 117 is pushed downward in the figure, and the longitudinal sectional shape is elastically deformed from a circular shape to an elliptical shape. At the same time, it is projected onto the sheet conveyance path. The protruding portion is an annular contact point contact portion 118, and the annular contact point contact portion 118 is protruded so as to slightly block the sheet conveyance path.

  FIG. 11C shows a state where the leading edge of the sheet has reached the detection position of the front registration sensor 56, and the sheet is conveyed along the upper guide plate downstream side portion 28.

  FIG. 11D shows a state in which the leading edge of the sheet is in contact with the annular contact point 118 of the annular contact 117 that has already been decentered in the direction opposite to the sheet conveyance direction and protruded onto the sheet conveyance path. In this case, the annular contact 117 is slightly curved with respect to the rigidity of the sheet.

  FIG. 11E shows a state in which the leading edge of the sheet has reached the registration roller nip region 55 of the stopped registration roller pair 48. The annular contactor 117 absorbs the collision force of the sheet by elastically deforming it after coming into contact with the leading end of the sheet in FIG. The leading edge of the sheet reaches the registration roller nip area 55 by moving so as to slide on the outer periphery of the annular contact 117, and according to the timing when the front registration sensor 56 described in FIG. After a predetermined time has elapsed, the rotation of the conveying roller pair 23 is stopped, and a predetermined loop is formed, so that skew correction is performed.

  FIG. 12 is a diagram illustrating a state in which a low-rigidity sheet passes through the sheet conveying unit 20A according to the second embodiment of the present invention. The same reference numerals are used for the same components as those in FIG.

  In FIG. 12A, the leading end portion of the sheet having low rigidity conveyed from the conveying roller pair 23 is along the upper guide plate upstream side portion 27 by the restoring force of the sheet to become a plane, and the swing arm The state at the moment of contact with the upstream side portion 35 is shown. The shape from the leading end of the sheet to the conveying roller pair 23 on the upstream side is low in rigidity, so that the restoring force described above is weak and easily bent, so that it follows the upper guide plate upstream side portion 27.

  In FIG. 12B, the leading edge of the sheet has reached the swing arm apex portion 36. At that time, the swing arm 31 has a repulsive force of the swing arm spring 39 as a restoring force of the sheet having low rigidity. It does not rock to win. Therefore, the swing arm tip portion 38 does not swing the intermediate lever lever portion 116, and the integrated intermediate lever arch portion 113 does not swing. Therefore, the annular contact point 118 of the annular contactor 117 is on the sheet conveyance path. It will be in the state which does not stick out.

  FIG. 12C shows a state in which the leading edge of the sheet has reached the detection position of the front registration sensor 56, and the sheet is conveyed along the lower guide plate 29 by the restriction by the swing arm apex portion 36. .

  FIG. 12D shows a state in which the leading edge of the sheet passes through the vicinity of the annular contactor 117 that is retracted to a position that does not block the sheet conveyance path.

  FIG. 12E shows a state in which the leading edge of the sheet has reached the nip region 55 of the stopped pair of registration rollers 48. At this time, in accordance with the timing when the front registration sensor 56 described in FIG. 12C detects the leading edge of the sheet, the rotation of the conveying roller pair 23 stops after a predetermined time has elapsed, and a predetermined loop is formed, thereby performing the skew feeding. Correction is performed.

  In the above description, the sheet having high rigidity and the sheet having low rigidity are described. However, when plain paper having medium rigidity is transported, the swing arm 31 swings by an amount corresponding to the sheet rigidity. The moving arm tip 38 swings the intermediate lever 116 by that amount, and causes the annular contact point 118 to protrude by an amount suitable for the stiffness of the sheet.

  For the swing of the intermediate lever 116, a drive source such as an actuator may be provided separately. In that case, a sensor for detecting the displacement amount of the swing arm is provided, and the detection result is converted to the drive amount of the actuator. The effect of this invention can be show | played by converting.

  The annular contact 117 is preferably a flexible material whose outer peripheral shape is elastically deformed in response to an external force. Specifically, a resin film such as polyimide, an elastic resin, a vulcanized rubber, an elastomer, a metal It may be formed of foil or the like. Further, the outer surface of the annular contact 117 may be formed of these materials, and the inner surface may be formed of a foam material such as soft polyurethane, vulcanized rubber, or elastomer, or a solid material.

  In order to facilitate elastic deformation of the annular contact 117, it is preferable that the friction coefficient at the outer contact is larger than the friction coefficient at the inner contact of the annular contact 117. Therefore, the surface of the intermediate lever arch 113 facing the annular contact 117, the inner and outer circumferences of the annular contact 117, and the outer circumference of the registration driven roller 53 are maintained, for example, with Teflon. It is preferable to coat with a low-friction material such as (registered trademark) or to paste a low-friction material having a smooth surface state such as high-density polyethylene.

  As described above, according to the first embodiment of the present invention, before the conveyed sheet collides with the registration roller, the entry speed of the sheet into the registration roller is reduced by contacting the contact member. . Thereby, the collision force to the registration roller is reduced, and for example, the collision sound is reduced. And since the contact member protrudes when the front end of the sheet comes into contact with the swinging member, the collision force can be reduced at an appropriate timing.

  Furthermore, in the first embodiment of the present invention, the amount by which the contact member protrudes on the sheet conveyance path is changed according to the contact force of the sheet to the swing member, so that the collision occurs according to the stiffness of the sheet. The force can be reduced.

  Furthermore, in the first embodiment of the present invention, since the contact member protrudes by the swinging force of the swinging member, it does not require a driving source such as an actuator, and the collision force can be reduced according to the stiffness of the seat. it can.

  Furthermore, in the first embodiment of the present invention, the portion of the abutting member that abuts on the leading end of the sheet is divided into a plurality of portions in a direction orthogonal to the sheet conveyance direction, so that a plurality of abutting members are provided on the sheet. It becomes possible to make it contact, and it can prevent that a local stress arises in a sheet | seat.

  Furthermore, in the first embodiment of the present invention, since the plurality of swing members are provided, the contact members can swing separately, whereby the contact members are skewed and conveyed. On the other hand, it is possible to make contact with the leading edge of the sheet in a timely manner, and the skew of the sheet can be reduced.

  Furthermore, in the first embodiment of the present invention, the swinging member can be swung in a direction that follows the sheet conveying direction, and the contact point with the swinging member sheet becomes the sheet conveying direction by the swinging of the swinging member. Therefore, the occurrence of jam can be reduced.

  Further, according to the second embodiment of the present invention, the contact member has a hollow cylindrical shape and is provided coaxially between one of the divided registration rollers, so that the contact member contacts the sheet. The sheet is elastically deformed, and the leading end of the sheet can move so as to slide on the outer periphery of the contact member. Accordingly, it is possible to make contact with the sheet on the surface, and the contact time can be extended, so that the collision force can be further reduced. Further, since the contact point between the contact member and the sheet changes, there is an effect of preventing wear and damage of a specific part rather than contact at a specific point, and an effect of improving durability can be obtained.

1 is an overall view of an image forming apparatus of the present invention. It is a figure for demonstrating the behavior of the highly rigid sheet | seat which passes the sheet | seat conveyance part which concerns on 1st Embodiment of this invention. It is a figure for demonstrating the behavior of the sheet | seat with low rigidity which passes the sheet | seat conveyance part which concerns on 1st Embodiment of this invention. It is a perspective view of the sheet conveyance part which concerns on 1st Embodiment of this invention. It is a perspective view of the sheet conveyance part which concerns on the modification of 1st Embodiment of this invention. It is a front view of the sheet conveyance part which concerns on the modification of 1st Embodiment of this invention. It is a perspective view of the sheet conveyance part which concerns on 2nd Embodiment of this invention. It is a front view of the sheet conveyance part which concerns on 2nd Embodiment of this invention. FIG. 6 is an enlarged view of a vicinity of a registration roller pair of a sheet conveying unit according to a second embodiment of the present invention. FIG. 6 is an enlarged view of a vicinity of a registration roller pair of a sheet conveying unit according to a second embodiment of the present invention. It is a figure for demonstrating the behavior of the highly rigid sheet | seat which passes the sheet | seat conveyance part which concerns on 2nd Embodiment of this invention. It is a figure for demonstrating the behavior of the sheet | seat with low rigidity which passes the sheet | seat conveyance part which concerns on 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Paper feed part 11 Sheet material cassette 12 Sheet material bundle 13 Pickup roller 14 Feed roller pair 15 Feed roller 16 Reverse roller 20 Sheet conveyance part 21 Registration means 22 Collision force reduction means 23 Conveyance roller pair 24 Conveyance drive roller 25 Conveyance driven roller 26 Upper guide plate 27 Upper guide plate upstream side 28 Upper guide plate downstream side 29 Lower guide plate 30 Curved conveyance path 31 Oscillating arm 32 Oscillating arm fulcrum support unit 33 Oscillating arm rotating shaft unit 34 Oscillating arm rotating fulcrum Part 35 Oscillating arm upstream side 36 Oscillating arm apex part 37 Oscillating arm downstream side part 38 Oscillating arm tip part 39 Oscillating arm spring 40 Contact 41 Contactor fulcrum support part 42 Contactor shaft part 43 Contactor rotation Fulcrum part 44 contactor contact part 45 contactor lever part 46 contactor spring 47 registrar Roller front conveyance path 48 Registration roller pair 49 Registration drive roller 50 Registration drive roller small diameter portion 51 Registration drive roller shaft portion 52 Registration driven roller 53 Registration driven roller small diameter portion 54 Registration driven roller shaft portion 55 Registration roller nip region 56 Registration roller nip area 56 Rear registration sensor 58 Transfer path before transfer roller 59 Opening 60 Image forming unit 61 Image forming unit Y
62 Image creation unit M
63 Image forming unit C
64 Image creation unit BK
65 Photosensitive drum 66 Developing means 67 Exposure means 68 Charging means 69 Cleaning means 70 Transfer part 71 Primary transfer part Y
72 Primary transfer part M
73 Primary transfer part C
74 Primary transfer part BK
75 Intermediate transfer belt 76 Belt drive roller 77 Belt driven roller 78 Belt tension roller 79 Transfer roller 80 Opposing roller 90 Fixing portion 91 Fixing roller pair 92 Heating roller 93 Pressure roller 100 Image forming apparatus 110 Intermediate lever fulcrum support portion 111 Intermediate lever Shaft portion 112 Intermediate lever rotation fulcrum portion 113 Intermediate lever arch portion 114 First arch contact portion 115 Second arch contact portion 116 Intermediate lever lever portion 117 Annular contactor 118 Annular contactor contact portion 119 Annular contactor spring

Claims (8)

In a sheet conveying apparatus comprising a pair of registration rollers that abuts a fed sheet and corrects skew by forming a deflection on the sheet.
In the vicinity of the nip of the registration roller pair, a contact member that reduces the collision force of the sheet to the registration roller is provided,
Provided on the upstream side of the conveying path with respect to the contact member is a swinging member that contacts the leading end of the sheet and swings according to the rigidity of the sheet,
The sheet conveying apparatus, wherein the contact member protrudes onto a sheet conveying path when a leading edge of the sheet contacts the swinging member. The sheet conveying apparatus according to claim 1,
The sheet conveying apparatus according to claim 1, wherein an amount of protrusion of the abutting member on the sheet conveying path varies according to a contact force with which the sheet contacts the swinging member. The sheet conveying apparatus according to claim 1,
Having a curved curved conveying path;
The sheet conveying apparatus, wherein the swing member is disposed on the curved transport path, and is protruded onto the sheet transport path by a swinging force by which the swing member swings. The sheet conveying apparatus according to any one of claims 1 to 3,
A portion of the contact member that contacts the leading end of the sheet is divided into a plurality of portions in a direction orthogonal to the sheet transport direction. The sheet conveying apparatus according to claim 4,
A plurality of the swing members are provided in a direction orthogonal to the sheet transport direction, and each swing member independently swings. The sheet conveying apparatus according to any one of claims 1 to 5,
The swing member and the contact member are separate and each has a swing fulcrum,
The sheet conveying apparatus, wherein the swing member is in contact with the sheet on the downstream side in the sheet transport direction from the swing support point of the swing member . The sheet conveying apparatus according to any one of claims 1 to 6,
At least one of the pair of registration rollers is divided into a plurality in a direction perpendicular to the sheet conveying direction,
The contact member has a hollow cylindrical shape,
Arranged coaxially between the plurality of divided registration rollers,
A sheet conveying apparatus, wherein a leading end of a sheet is decentered in a direction opposite to a conveying direction of the sheet by contacting the swinging member, and the sheet is ejected onto a conveying path of the sheet. A sheet conveying device according to any one of claims 1 to 7,
An image forming apparatus comprising image forming means for forming an image on a sheet fed from the sheet conveying apparatus.

Images