JP2006290516A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus easily performing jamming processing by using simple structure to suppress increase in cost. <P>SOLUTION: In the image forming apparatus, a double-sided unit 60 is releasable from a device body 50 by using a rotational shaft 63 of a lower part of the device as a supporting point. Resist roller pair 18 is supported by the device body 50 and is left on a device body side when the double-sided unit 60 is released. A guide plate 42 outside a resist port is supported on a double-sided unit 60 side and is released together with the double-sided unit 60. A movement locus of the guide plate 42 in opening/closing the double-sided unit 60 does not interfere with the resist roller pair 18. Since the resist roller pair 18 is left in the device body, the parallelism and the pressurizing balance of the resist roller pair are not lost. Since the guide plate is released together with the double-sided unit 60, the jamming processing is facilitated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly to a technique for improving jam handling.

JP 2005-31352 A Japanese Patent Publication No.8-18724

  Some image forming apparatuses such as copiers, printers, facsimiles, and the like are provided with a paper conveyance path in the vicinity of the registration rollers that can be opened to facilitate jam handling at the registration rollers. For example, in FIGS. 9 and 10 of Patent Document 1, the sheet conveying path before and after the registration roller pairs 701 and 702 (703) is opened by opening the automatic duplex device 200 and the secondary transfer device 400. It is disclosed.

  However, in the device described in Patent Document 1, a member on one side (outside) of the guide plate for guiding the paper to the registration nip remains in the nip portion (under the outer roller 702 in FIG. 10), and jammed. There is a problem that the visibility of the paper is poor and the jam handling property is not good.

  On the other hand, Patent Document 2 discloses a configuration in which the outer roller 13b constituting the registration roller pair is opened together with the duplex unit and separated from the inner roller 13a (FIG. 2).

  However, in the configuration in which the outer roller of the registration roller pair is separated from the inner roller in this way, it is difficult to achieve a pressure balance when the opening unit is closed, and the configuration of each part is made to satisfy the parallelism of the registration roller pair. There is a problem that high accuracy is required and the cost of the apparatus is increased.

  It is an object of the present invention to provide an image forming apparatus that solves the above-described problems in a conventional image forming apparatus and that can easily perform jam processing with a simple configuration while suppressing an increase in cost.

  According to the present invention, there is provided a sheet conveying unit that is disposed in a sheet conveying path and that conveys a sheet between a pair of rotating members, a guide member that guides the sheet to the sheet conveying unit, and an apparatus main body. And an opening / closing part that can be opened and closed with respect to the image forming apparatus, wherein the sheet conveying path in the vicinity of the sheet conveying means is opened by opening the opening / closing part. A guide plate that is supported and guides the paper conveyance path on the opening / closing portion side of the guide member is supported by the opening / closing portion, and a movement trajectory of the guide plate when the opening / closing portion is opened / closed to the paper conveyance means. It is solved by being configured not to interfere.

  In addition, the pivot point of the opening / closing unit is provided at a position lower than the sheet conveying unit, and of the pair of rotating members of the sheet conveying unit, the rotating member on the opening / closing unit side is a rotation on the apparatus body side. It is preferable to be arranged at a position higher than the moving member.

Moreover, it is preferable that the rotation member on the opening / closing portion side of the pair of rotation members of the paper transport unit has a smaller diameter than the rotation member on the apparatus main body side.
Further, according to the present invention, there is provided, according to the present invention, a sheet conveying unit that is disposed in a sheet conveying path and conveys a sheet between a pair of rotating members, a guide member that guides the sheet to the sheet conveying unit, An image forming apparatus having an opening / closing section provided to be openable / closable with respect to the apparatus main body, wherein the sheet conveying path in the vicinity of the sheet conveying means is opened by opening the opening / closing section. A guide plate that is supported by the main body and guides the paper conveyance path on the opening / closing section side of the guide member is supported on the apparatus main body side so as to be rotatable, and the paper conveyance path on the upstream side of the paper conveyance means is opened. It is solved by being configured to be possible.

Further, it is preferable that the guide plate is provided so as to be rotatable about a rotation shaft of the rotation member on the opening / closing portion side of the pair of rotation members of the sheet conveying unit.
The guide plate is preferably provided with a notch window.

Further, it is preferable that a film member is attached to the surface of the guide plate on the side of the paper conveyance path.
The film member is preferably a transparent film.

Further, it is preferable that the downstream end of the film member in the sheet conveyance direction is provided so as to protrude from the downstream end of the guide plate in the sheet conveyance direction.
Further, it is preferable that the sheet conveying means is a pair of registration rollers.

Further, it is preferable that the pair of rotating members of the sheet conveying means has a friction coefficient of one rotating member higher than that of the other rotating member.
The one rotating member is preferably a driving roller, and the other rotating member is preferably a driven roller.

Further, it is preferable that a transfer device for transferring the image carried on the image carrier of the image forming apparatus onto the recording medium is mounted on the opening / closing unit.
Further, it is preferable that a paper reversing device for reversing the front and back of the paper is mounted on the opening / closing section.
Further, it is preferable that a manual sheet feeding device is mounted on the opening / closing section.

  According to the image forming apparatus of the first and fourth aspects, the parallelism / pressure balance of the pair of rotating members constituting the sheet conveying unit is not changed, and the apparatus configuration is simple and easy at low cost. It is possible to provide an image forming apparatus capable of performing jam processing.

  According to the configuration of the second aspect, the rotation fulcrum of the opening / closing portion is provided at a position lower than the sheet conveying means, and the rotation member on the opening / closing portion side is disposed at a position higher than the rotation member on the apparatus main body side. Even when the movement path of the guide plate is configured not to interfere with the paper transporting means, the guide plate can be disposed as close as possible to the nip portion, and the paper can be reliably guided.

  According to the configuration of the third aspect, the rotating member on the opening / closing portion side has a smaller diameter than the rotating member on the apparatus main body side. The guide plate can be disposed as close as possible, and the paper can be reliably guided.

  According to the fifth aspect of the present invention, the guide plate is provided so as to be rotatable about the rotation shaft of the rotation member on the opening / closing portion side, so that the configuration in which the guide plate can be opened is facilitated. Further, when the guide plate is rotated, it can be prevented from interfering with the rotating member.

  According to the configuration of the sixth aspect, since the notch window is provided in the guide plate, the paper conveyance path inside the guide plate and the paper in the guide plate can be seen, the paper state can be grasped, and the jam processing is easy. become.

According to the seventh aspect of the present invention, since the film member is attached to the surface of the guide plate on the side of the sheet conveyance path, the sheet can be guided to the nip portion more smoothly.
According to the configuration of the eighth aspect, since the film member is a transparent film, the visibility when the notch window is provided in the guide plate is not impaired.

  According to the ninth aspect of the present invention, the downstream end of the film member in the sheet conveyance direction protrudes from the downstream end of the guide plate in the sheet conveyance direction, so that the sheet can be guided to a position closer to the nip. it can.

  According to the configuration of the tenth aspect, the parallelism and pressure balance of the registration roller pair are not disturbed, and the sheet can be reliably sent out. Further, it is possible to easily perform jam processing at the resist portion.

  According to the configuration of the eleventh aspect, since the friction coefficient of one rotating member is higher than the friction coefficient of the other rotating member, it is possible to achieve both the ensuring of sheet transportability and the ability of entering the sheet into the nip portion. it can.

  According to the configuration of the twelfth aspect, by using the rotating member having the higher friction coefficient as the driving roller, it is possible to reliably convey the sheet.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional configuration diagram showing an outline of a full-color printer as an example of an image forming apparatus according to the present invention. In the full-color printer 100 shown in this figure, an intermediate transfer belt 11 wound around a plurality of rollers is disposed at a substantially central portion of the apparatus main body, and 4 along the lower running side of the intermediate transfer belt 11. Image forming units 10 (M, C, Y, Bk) are arranged.

  Each image forming unit 10 includes a photosensitive drum 1 as an image carrier. A charging unit, a developing device, a cleaning unit, and the like are disposed around the photosensitive drum 1, and a transfer roller 12 as a primary transfer unit is disposed inside the intermediate transfer belt 11 at a position facing each photosensitive drum 1. Is provided. In the case of this example, the four image forming units 10 have the same structure, but the developer colors handled by the developing devices of the respective image forming units are different from four colors of magenta, cyan, yellow, and black. . In the case of this example, the four image forming units 10 are arranged in the order of magenta, cyan, yellow, and black from the left in the drawing. Each image forming unit 10 is detachably attached to the apparatus main body as a process cartridge.

  An optical writing device 14 is provided below the image forming unit 10. Although not shown, the optical writing device 14 has a polygon mirror, a group of mirrors, etc., and irradiates the surface of the photosensitive drum 1 of each color image forming unit with light-modulated laser light. The optical writing device may be provided individually for each image forming unit 10, but using a common optical writing device is advantageous in terms of cost. In this example, the intermediate transfer belt 11 and the optical writing device 14 are also unitized, and are configured to be detachable from the apparatus main body.

  Two stages of paper feed cassettes 15a and 15b are set at the lower part of the apparatus, and paper feed means 16a and 16b corresponding to the respective paper feed cassettes are provided. Each of the sheet feeding means 16a and 16b includes a calling roller, a supply roller, and a separation roller. Conveying roller pairs 17 and 17 are provided for conveying a recording medium such as transfer paper (hereinafter referred to as paper) fed by the paper feeding means 16a and b. A registration roller pair 18 is provided above the upper conveyance roller pair 17 (on the downstream side in the paper conveyance direction). Above the registration roller pair 18, a transfer roller 19 as a secondary transfer unit is provided facing a transfer counter roller 13, which is one of the rollers around which the intermediate transfer belt 11 is stretched, and a secondary transfer unit. Is forming.

  A fixing device 20 is provided above the secondary transfer unit. Above the fixing device 20, first to third switching claws 21, 22, and 23 for switching the sheet conveyance direction are arranged. Yes. Each switching claw 21 to 23 is switched to a position indicated by a solid line and a virtual line in FIG. 2 by an actuator such as a solenoid (not shown). Reference numerals 24 to 27 denote transport roller pairs appropriately disposed in the paper transport path. Reference numerals 35 to 41 are paper sensors appropriately disposed in the paper conveyance path. Note that the paper conveyance path is appropriately guided by a member (not labeled) such as a guide plate.

  The upper surface of the apparatus main body 50 is configured as a paper discharge tray 30, and a paper discharge roller pair 29 for discharging paper to the paper discharge tray 30 is provided at the upper left of the fixing device 20.

  In the duplex unit 60, a switchback transport path 61 and a refeed path 62 are formed. A first reverse roller pair 31 is provided at the inlet (upper side of the apparatus) of the switchback conveyance path 61, and a second reverse roller pair 32 is provided in the middle of the switchback conveyance path 61. The first and second reversing roller pairs 31 and 32 are configured to be rotatable forward and backward. A pair of conveying rollers 26 and 27 is arranged at a position where the refeeding path 62 is substantially divided into three equal parts. The above-described third switching claw 23 is disposed immediately next to the first reversing roller pair 31 and positioned at an entry portion from the switchback conveyance path 61 to the refeeding path 62.

  A manual feed tray 33 is provided on the side surface of the duplex unit 60 so that it can be pulled out and stored. FIG. 1 shows a state where the manual feed tray 33 is pulled out. In order to feed paper from the manual feed tray 33, a paper feed means 34 including a calling roller, a supply roller, and a separation roller is provided. A re-feed roller 28 is disposed on the side of the paper feed means 34 and inside the apparatus. The driven rollers are pressed against the upper and lower sides of the refeed roller 28, respectively. The re-feed roller 28 is configured to be able to rotate forward and backward. When the paper is re-feeded from the re-feed path 62, the re-feed roller 28 is rotated counterclockwise in the drawing to feed the paper from the manual feed tray 33. In this case, it is rotated clockwise in the figure.

An image forming operation in the full color printer 100 of this example configured as described above will be briefly described.
The photosensitive drum 1 of the image forming unit 10 is rotated in the clockwise direction in the figure by a driving means (not shown), and the surface of the photosensitive drum 1 is uniformly charged to a predetermined polarity by the charging means. The charged photoconductor surface is irradiated with laser light from the optical writing device 14, whereby an electrostatic latent image is formed on the photoconductor drum 1 surface. At this time, the image information exposed on each photosensitive drum 1 is single-color image information obtained by separating a desired full-color image into magenta, cyan, yellow, and black color information. Each color toner is applied from the developing device to the electrostatic latent image formed in this way, and visualized as a toner image.

  Further, the intermediate transfer belt 11 is driven to run counterclockwise in the drawing as indicated by an arrow, and each color toner image is sequentially transferred from the photosensitive drum 1 to the intermediate transfer belt 12 by the action of the primary transfer roller 12 in each image forming unit 10. Overprinted. In this way, the intermediate transfer belt 11 carries a full-color toner image on the surface thereof.

  Note that any one of the image forming units 10 can be used to form a single-color image or a two-color or three-color image. In the case of monochrome printing, image formation is performed using the rightmost Bk unit in the figure among the four image forming units.

  The residual toner adhering to the surface of the photosensitive drum after the toner image is transferred is removed from the surface of the photosensitive drum by the cleaning device, and then the surface is subjected to the action of the static eliminator to initialize the surface potential. Ready for image formation.

  On the other hand, the paper is selectively fed from the paper feed cassettes 15a, 15b or the manual feed tray 33, and the toner image carried on the intermediate transfer belt 11 is timed by the registration roller pair 18 to the secondary transfer position. Sent out. In this example, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the surface of the intermediate transfer belt is applied to the transfer roller 19, whereby the toner image on the surface of the intermediate transfer belt is collectively transferred onto the paper. When the sheet on which the toner image has been transferred passes through the fixing device 20, the toner image is fused and fixed to the sheet by heat and pressure. The fixed transfer material is discharged by a paper discharge roller 29 to a paper discharge unit 30 formed on the upper surface of the apparatus main body 1. The sheet transport path (when the paper is fed from the paper feed cassettes 15a and 15b) during single-sided printing is indicated by a solid line [1] in FIG.

  An optional paper discharge tray (for example, a 4-bin tray having a sorting function) can be mounted on the upper surface of the apparatus above the second switching claw 22, and the fixed sheet can be discharged to the optional tray (not shown). It is. A paper transport path (after passing through the fixing device) when paper is discharged to the option tray is indicated by a broken line [2] in FIG.

  When printing on both sides of the sheet, the sheet having the toner image fixed on one side of the sheet is caused to enter the switchback conveyance path 61 by appropriately switching the first to third switching claws 21 to 23. In this case, the first and second switching claws 21 and 22 are switched to the positions of the virtual lines in FIG. Moreover, the 3rd switching nail | claw 23 is switched to the position of the continuous line of FIG. Further, the first and second reversing roller pairs 31 and 32 are rotated in the forward direction (clockwise in FIG. 1). A conveyance path (however, after the conveyance roller pair 25) when the sheet enters the switchback conveyance path 61 is indicated by a two-dot chain line [3] in FIG.

  When the sensor 40 detects the trailing edge of the sheet that has entered the switchback conveyance path 61, the first and second reversing roller pairs 31, 32 are rotated in the reverse direction (counterclockwise in FIG. 1) to reverse the sheet. At this time, by switching the third switching claw 23 to the position of the imaginary line in FIG. 2, the reversed paper is sent to the refeed path 62.

  The re-feeding path 62 is joined at the lower end of the sheet feeding path from the manual feed tray 33, and further joined at the back side of the re-feeding roller 28 with the sheet feeding path from the sheet feeding cassettes 15a and 15b. The paper is transported in the refeed path 62 by the transport roller pairs 26 and 27, and further sent to the registration roller pair 18 by the refeed roller 28. A sheet conveyance path (however, from the third switching claw 23 to a portion joining the solid line [1]) passing through the refeed path 62 is indicated by a one-dot chain line [4] in FIG. In addition, a sheet conveyance path when the sheet is fed from the manual feed tray 33 (up to a position where the sheet re-feed roller 28 is removed) is indicated by a dotted line [5] in FIG.

  By passing the paper reversed by the switchback transport path 61 through the refeed path 62, the front and back of the paper are reversed, and the toner image is transferred from the intermediate transfer belt 11 to the back of the paper, and the back image is fixed to the fixing device. By fixing at 20, the paper carrying the images on both the front and back sides is discharged to the paper discharge tray 30 or an optional tray (not shown), thereby completing double-sided printing.

  Now, in the printer 100 of this example, the duplex unit 60 is provided so as to be swingable about a rotation shaft 63 provided at the lower part thereof, and the duplex unit 60 can be opened and closed with respect to the apparatus main body 50. FIG. 3 shows a state where the duplex unit 60 is opened. The duplex unit 60 is supported by the apparatus main body 50 by a link mechanism (not shown), and stops at a predetermined position when opened. Further, in order to reduce the opening / closing force of the double-sided unit 60, it is preferable to provide a damper means in the link mechanism that supports the double-sided unit 60. As the damper means, one using a spring, an oil damper or the like can be used.

  As included in the duplex unit 60 and opened and closed with respect to the apparatus main body 50, a guide plate (not shown) that forms the switchback conveyance path 61, a part of the guide plates 66 that form the refeed path 62, In addition to the transfer unit 64, there are a third switching claw 23, first and second reversing roller pairs 31 and 32, a manual feed tray 33, its paper feeding means 34, a refeed roller 28, and the like. The driven rollers 17 b and 17 b of the two transport roller pairs 17 and 17 are members included in the duplex unit 60 and are opened together with the duplex unit 60.

  The registration roller pair 18 is supported on the apparatus main body side and remains on the apparatus main body side even when the duplex unit 60 is opened. However, of the guide plates 42 and 43 that are provided on both sides of the paper conveyance path before the registration nip and guide the conveyed paper to the registration roller pair 18, the outer guide plate 42 is provided on the duplex unit 60. It is supported by the transfer unit 64 and opened together with the duplex unit 60 as shown in FIG. The inner guide plate 43 is supported on the apparatus main body side and remains on the apparatus main body side even when the duplex unit 60 is opened.

  In the state where the duplex unit 60 is closed as shown in FIG. 1, the secondary transfer roller 19 is pressed against the intermediate transfer belt 11 so as to face the transfer counter roller 13, and the driven rollers 17 b and 17 b of the two transport roller pairs 17. Are brought into pressure contact with the respective drive side rollers 17a and 17a and become operable.

  When the duplex unit 60 is opened as shown in FIG. 3, the secondary transfer roller 19 is separated from the intermediate transfer belt 11 (opposing roller 13), and the driven rollers 17b and 17b of the two transport roller pairs 17 are driven respectively. The sheet conveyance path before and after the registration roller pair 18 is opened apart from the side rollers 17a and 17a.

  As shown in an enlarged view in FIG. 4, the outer guide plate 42 in front of the registration nip rotates about a rotation shaft 63 that is a rotation fulcrum of the duplex unit 60. At this time, the upper end of the guide plate 42 is configured not to interfere with the registration driven roller 18b which is an outer roller of the registration roller pair. In order to prevent the guide plate 42 from interfering with the resist driven roller 18b when the guide plate 42 is opened, the resist follower roller 18b, which is the outer roller of the resist roller pair, is disposed on the inside in order to arrange the outer guide plate 42 as close as possible to the resist nip. The resist driving roller 18a is disposed at a position higher than the registration driving roller 18a so as to be in pressure contact with the registration driving roller 18a. As a result, the sheet feeding direction by the registration roller pair 18 is slightly inward (upside of the apparatus) from the vertically upper side, but the apparatus is configured such that the secondary transfer unit is positioned in the sheet feeding direction by the registration roller pair 18. is doing.

  As described above, in this embodiment, by opening the duplex unit 60 as shown in FIG. 3, the sheet is conveyed from the lower conveying roller pair 17 to the registration roller pair 18 and from the registration roller pair 18 to the fixing device 20. The path is opened, and jam processing can be easily performed. Further, since the outer guide plate 42 in front of the registration roller pair 18 is opened together with the duplex unit 60, the processing of the jammed paper generated in the registration portion can be performed very easily.

  Since the registration roller pair 18 remains on the apparatus main body side when the duplex unit 60 is opened, the parallelism and pressure balance of the registration roller pair are not changed, and the apparatus cost is not increased. Further, no special device or the like is required for mounting the guide plate 42, and the apparatus configuration can be simplified.

  In this embodiment, the guide plates 42 and 43 are sheet metal (metal thin plates), but may be made of resin. In that case, it is also possible to integrate with a nearby resin component. For example, the outer guide plate 42 can be configured as a part of the transfer unit 64. A film member having a low frictional resistance, such as Mylar (trade name) film, may be mounted on the opposing surfaces of the guide plates 42 and 43 (surface for guiding paper). In that case, the front end (upper end) of the film protrudes from the upper ends of the guide plates 42 and 43 and is brought closer to the resist nip, whereby the sheet can be guided to the resist nip more reliably. Further, the guide plates 42 and 43 themselves can be formed of a film-like sheet member.

  Further, by arranging the registration driven roller 18b which is the outer roller of the registration roller pair at a position higher than the inner registration driving roller 18a, the movement locus of the outer guide plate 42 does not interfere with the registration driven roller 18b which is the outer roller. Even in such a configuration, the outer guide plate 42 can be disposed closer to the registration nip, and the sheet can be reliably guided to the registration nip.

  Also, in this example, the diameter of the resist driven roller 18b, which is the outer roller of the pair of dies rollers, is made smaller than the inner resist driving roller 18a, so that the movement path of the outer guide plate 42 is the resist driven roller 18b, which is the outer roller. Even when configured so as not to interfere with each other, the outer guide plate 42 can be disposed closer to the registration nip, and the sheet can be reliably guided to the registration nip.

  By the way, in this embodiment, the registration roller pair 18 has a configuration in which a registration driving roller 18a is disposed on the apparatus main body side and a registration driven roller 18b is disposed on the outside. As the resist driving roller 18a, a roller having a high friction coefficient such as a rubber roller or a grindstone roller having a rough surface is used. The resist driven roller 18b is a roller having a low friction coefficient such as a metal roller or a resin roller. As described above, the two roller members constituting the registration roller pair 18 are configured by combining a material having a high friction coefficient and a material having a low friction coefficient, thereby ensuring sheet conveyance and serving as a pressure contact portion between both rollers. The paper penetration into the registration nip is improved to prevent registration and jamming accurately.

  Next, a description will be given of a second embodiment in which the guide plate of the resist portion is supported on the apparatus main body side (not opened together with the duplex unit). Since the basic configuration of the image forming apparatus according to the second embodiment is the same as that of the first embodiment described above, overlapping description will be omitted, and different portions will be mainly described.

  In the second embodiment, as shown in FIG. 5, the guide plate 42 provided in front (upstream side) of the registration roller pair 18 is supported by the apparatus main body 50 together with the opposed inner guide plate 43, and the duplex unit 60 is Even when it is opened, it remains on the apparatus main body side together with the registration roller pair 18.

  In the second embodiment, the double-sided unit 60 includes a guide plate (no reference) that forms the switchback conveyance path 61 and a refeed path 62 that are opened and closed with respect to the apparatus body 50. In addition to the guide plate 66 and the transfer unit 64, there are a third switching claw 23, first and second reversing roller pairs 31 and 32, a manual feed tray 33, its paper feed means 34, and a refeed roller 28. The driven rollers 17 b and 17 b of the two transport roller pairs 17 and 17 are members included in the duplex unit 60 and are opened together with the duplex unit 60.

  FIG. 6 is an enlarged view of the vicinity of the registration roller pair 18. As shown in this figure, in the second embodiment, the driving roller 18a is disposed on the outer side (the duplex unit 60 side), and the driven roller 18b is disposed on the apparatus main body side. Guide plates 142 and 143 are provided immediately upstream of the registration roller pair 18 to guide the paper entering the registration nip. A registration sensor 37 is arranged inside the guide plate 143 on the apparatus main body side (inside the apparatus). In this example, the registration sensor 37 is a reflection type photosensor, and a hole 143 a for allowing detection light to pass therethrough is provided in the guide plate 143. When there is a sheet in the registration unit, the detection light from the registration sensor 37 is reflected on the sheet through the hole 143 a of the guide plate 143 and is incident on the registration sensor 37 to detect the sheet. When there is no sheet in the registration unit, the detection light from the registration sensor 37 passes through the hole 43a of the guide plate 143, and further from the hole 142a provided in the opposing outer guide plate 142, the duplex unit 60 (transfer unit). 64) The false detection is prevented by running in.

  Transparent films 144 and 145 are affixed to the opposing surfaces (surfaces on the paper conveyance path side) of both guide plates 142 and 143. For example, Mylar (trade name) can be used as the transparent film. The leading ends of the transparent films 144 and 145 are provided so as to protrude from the leading ends of the guide plates 142 and 143 and to be positioned in the immediate vicinity of the resist nip. The transparent films 144 and 145 having low frictional resistance are configured to reliably guide the paper to the resist nip.

  Further, the outer (both sides unit side) guide plate 142 is swingably provided with the shaft 18c of the registration driving roller 18a as a rotation fulcrum, and when the jam processing is performed at the registration portion, as indicated by a virtual line in the figure. By rotating the guide plate 142, the sheet conveyance path on the downstream side of the registration roller pair 18 is opened, and the jam processing can be easily performed.

  Further, as shown in FIG. 7, the outer guide plate 142 is provided with a notch window 142b for visually confirming the jammed paper at the resist portion. When the jam occurs on the front side of the registration roller pair 18 by the notch window 142b, the jammed paper can be easily visually recognized, and the jam processing can be easily performed. Of course, when the paper jammed before the registration roller pair 18 is removed, the jam processing can be easily performed by rotating the outer guide plate 142 as described with reference to FIG.

  Thus, in the second embodiment, the guide plate 142 provided in the resist portion is supported on the apparatus main body side and is not opened together with the duplex unit 60. However, the guide plate 142 is provided with the notch window 142b, and the guide Since the plate 142 is configured to be rotatable, the visibility of the jammed paper and the removal of the jammed paper when a paper jam occurs in the registration unit are improved, and the jam processing is facilitated.

  Also in the second embodiment, since the registration roller pair 18 remains on the apparatus main body side, the parallelism and pressure balance of the registration roller pair do not get out of order, and the apparatus cost does not increase. Further, since the transparent films 144 and 145 having a small friction coefficient are attached to both the guide plates 142 and 143, and the leading ends thereof protrude from the leading ends of the guide plates 142 and 143 and extend to the immediate vicinity of the registration nip, the paper Can be more reliably guided to the resist nip.

  In addition, by arranging the registration driving roller 18a, which is the outer roller of the registration roller pair, at a position higher than the inner registration driven roller 18b, the outer guide plate 142 can be arranged closer to the registration nip, and the sheet can be reliably secured. To the resist nip.

  Further, in this example, the outer guide plate 42 can be disposed closer to the resist nip by making the diameter of the resist driving roller 18a, which is the outer roller of the pair of dies rollers, smaller than the inner resist driven roller 18b. The sheet can be reliably guided to the registration nip.

  Also in the second embodiment, the registration roller pair 18 uses a high friction coefficient such as a rubber roller or a grindstone roller with rough surface properties as the driving roller 18a. The driven roller 18b is a roller having a low friction coefficient such as a metal roller or a resin roller. The two roller members constituting the registration roller pair 18 are configured by combining a material having a high coefficient of friction and a material having a low coefficient of friction, thereby ensuring the sheet conveyance property and at the same time the registration nip that is the pressure contact portion of both rollers. The paper penetration is improved to ensure accurate resist and jam prevention.

Although the present invention has been described above with reference to the illustrated examples, the present invention is not limited thereto.
The material, shape, size, and the like of the guide plate are arbitrary and can be appropriately changed within the scope of the present invention. Also, a film member may be attached to the opposing surfaces (surfaces on the paper conveyance path side) of the guide plates (42, 43) of the first embodiment of FIGS. In that case, the paper guide to the nip becomes more reliable by projecting the front end of the film from the front end of the guide plate. The material, shape, and the like of the rollers that constitute the sheet conveying means (registration rollers) are merely examples, and any can be employed.

  The present invention can also be applied to a monochrome apparatus having a single image carrier, or a color apparatus having a plurality of developing devices arranged around a single image carrier. Of course, the image forming apparatus is not limited to a printer, and may be a copying apparatus or a facsimile, or a multi-function machine having a plurality of functions. Further, the image forming method is not limited to the electrophotographic method, and the present invention can be applied to any image forming method apparatus.

1 is a cross-sectional configuration diagram illustrating an outline of a full-color printer which is an example of an image forming apparatus according to the present invention. FIG. 6 is a diagram illustrating a paper conveyance path in the printer. It is a figure which shows a mode that the duplex unit of the printer was open | released. It is an enlarged view showing the vicinity of a registration roller. It is a cross-sectional block diagram which shows the outline of the image forming apparatus of 2nd Example. FIG. 3 is an enlarged view showing the vicinity of a registration roller of the image forming apparatus. It is a side view of the vicinity of a registration roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming unit 11 Intermediate transfer belt 18 Registration roller pair 18a Registration drive roller 18b Registration driven roller 37 Registration sensor 42, 142 Outer guide plate 43, 143 Inner guide plate 60 Double-sided unit 63 Double-sided unit rotating shaft 64 Transfer unit 100, 200 Full color printer 142b Notch window 144,145 Transparent film

Claims (15)

A sheet conveying unit that is disposed in the sheet conveying path and conveys the sheet by sandwiching the sheet between a pair of rotating members, a guide member that guides the sheet to the sheet conveying unit, and a device that can be opened and closed with respect to the apparatus main body. An image forming apparatus having an opening and closing unit, wherein the sheet conveying path near the sheet conveying unit is opened by opening the opening and closing unit;
The paper conveying means is supported by the apparatus main body,
A guide plate that guides the paper conveyance path on the opening / closing portion side of the guide member is supported by the opening / closing portion, and a movement locus of the guide plate at the time of opening / closing the opening / closing portion does not interfere with the paper conveyance means. An image forming apparatus configured to be configured. The pivot point of the opening / closing part is provided at a position lower than the sheet conveying means,
The rotation member on the opening / closing section side of the pair of rotation members of the paper transport unit is disposed at a position higher than the rotation member on the apparatus main body side. Image forming apparatus. 3. The image according to claim 1, wherein, of the pair of rotating members of the paper transport unit, the rotating member on the opening / closing portion side has a smaller diameter than the rotating member on the apparatus main body side. Forming equipment. A sheet conveying unit that is disposed in the sheet conveying path and conveys the sheet by sandwiching the sheet between a pair of rotating members, a guide member that guides the sheet to the sheet conveying unit, and a device that can be opened and closed with respect to the apparatus main body. An image forming apparatus having an opening and closing unit, wherein the sheet conveying path near the sheet conveying unit is opened by opening the opening and closing unit;
The paper conveying means is supported by the apparatus main body,
A guide plate that guides the sheet conveyance path on the opening / closing section side of the guide member is supported on the apparatus main body side so as to be rotatable, and is configured to be able to open the sheet conveyance path on the upstream side of the sheet conveyance unit. An image forming apparatus. The guide plate is provided so as to be pivotable about a pivot shaft of a pivot member on the opening / closing section side of the pair of pivot members of the sheet conveying means. 5. The image forming apparatus according to 4. The image forming apparatus according to claim 4, wherein the guide plate is provided with a notch window. The image forming apparatus according to claim 1, wherein a film member is affixed to a surface of the guide plate on a paper conveyance path side. The image forming apparatus according to claim 7, wherein the film member is a transparent film. 9. The image forming apparatus according to claim 7, wherein a tip of the film member on the downstream side in the paper conveyance direction is provided so as to protrude from a tip on the downstream side of the guide plate in the paper conveyance direction. The image forming apparatus according to claim 1, wherein the sheet conveying unit is a pair of registration rollers. 5. The pair of rotating members of the sheet conveying unit has a coefficient of friction of one rotating member higher than a coefficient of friction of the other rotating member. Image forming apparatus. 12. The image forming apparatus according to claim 11, wherein the one rotating member is a driving roller and the other rotating member is a driven roller. The image forming apparatus according to claim 1, wherein a transfer device that transfers an image carried on an image carrier of the image forming apparatus onto a recording medium is mounted on the opening / closing unit. The image forming apparatus according to claim 1, wherein a paper reversing device for reversing the front and back of the paper is mounted on the opening / closing unit. The image forming apparatus according to claim 1, wherein a manual sheet feeding device is mounted on the opening / closing unit.

Images