JP5796446B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that forms an image on an electrophotographic method while conveying the recording medium by an endless belt, and more specifically, guides the recording medium on which the image is formed to a fixing unit. The present invention relates to an image forming apparatus that heats and fixes an image.

  2. Description of the Related Art Conventionally, in an image forming apparatus that forms an image on an electrophotographic method while conveying a sheet as a recording medium by an endless belt, the sheet after image formation is conveyed from the endless belt to a fixing device. The image formed on the paper is heat-fixed. Further, in this type of image forming apparatus, it has been proposed that the rear end portion of a guide for guiding a sheet from an endless belt to a fixing device can be swung (for example, see Patent Document 1). In that case, the paper discharge path can be made flexible, and even when a stiff paper is bent between the endless belt and the fixing device, the bending can be allowed.

JP 2010-197652 A

  On the other hand, in the image forming apparatus as described above, an image is formed by electrophotography using a transfer current while adsorbing and conveying a sheet to a sheet conveying belt (endless belt) functioning as a transfer belt. When the paper after image formation is suddenly peeled from the endless belt, so-called peeling discharge occurs. That is, for example, a discharge occurs between the sheet peeled toward the fixing device by the guide and the endless belt, and the image formed on the sheet is disturbed. Although giving flexibility to the paper discharge path as in Patent Document 1 may be effective in suppressing peeling discharge depending on the mode, Patent Document 1 does not make such consideration.

  Further, the peeling discharge as described above is more likely to occur on a paper having a specific width that is stiff, such as a postcard or various cards, as compared to general high-quality paper such as A4. Accordingly, the present invention has been made for the purpose of suppressing peeling discharge by suppressing abrupt peeling from an endless belt after image formation on a recording medium of at least a specific width.

  The image forming apparatus of the present invention made to achieve the above object includes an endless belt that is laid between a plurality of rollers and is rotationally driven to convey a recording medium, and a recording medium that is conveyed by the endless belt And an image forming means for forming an image by electrophotography using a transfer current, and a position shifted in the peeling direction of the recording medium from the extended surface of the recording surface with respect to the recording surface of the recording medium by the endless belt A fixing unit that heats and fixes the image formed on the recording medium by the image forming unit, and a guide unit that guides the recording medium on which the image is formed by the image forming unit to the fixing unit. The guide means is provided so as to be inclined in the fixing means direction with respect to the extended surface, and a width perpendicular to the conveyance direction by the endless belt is a first width. A first guide for guiding the recording medium to the fixing unit; and the first guide being recessed or notched along the recording medium conveyance direction, leaving at least both ends of the first width. The second recording medium having a second width smaller than the first width is guided such that a sheet guide angle in the fixing unit direction with respect to the extended surface is smaller than that of the first guide. A second guide, provided at an intermediate position in the peeling direction between the first guide and the second guide, to prevent the second recording medium guided by the second guide from floating; and And a pressing portion that does not protrude on the surface of the first guide.

  In the image forming apparatus of the present invention configured as described above, a recording medium on which an image is formed by an image forming unit by electrophotographic method using a transfer current when conveyed by an endless belt is fixed by a guide unit. Guided by means. The fixing means is provided at a position offset from the extended surface of the recording surface in the peeling direction of the recording medium with respect to the recording surface of the recording medium by the endless belt, and the image of the recording medium guided by the fixing means is displayed. Fix by heating.

  Here, the guide means includes a first guide, a second guide, and a pressing portion, and the first recording medium whose width perpendicular to the conveying direction by the endless belt is the first width, and the first recording medium. The second recording medium having the second width smaller than the first width is guided to the fixing unit through a different path. The first width is a width corresponding to a recording medium having a relatively low waist such as A4 high-quality paper, and the second width is a relatively strong waist such as a business card, a postcard, and a greeting card. The width corresponds to the recording medium. The first width and the second width are set in advance at the time of design according to the lifestyle of the country and region where the image forming apparatus is used and the size of the image forming apparatus itself.

  The second guide for guiding the second recording medium to the fixing means is configured by denting or notching the first guide in the recording medium conveyance direction leaving at least both ends of the first width. Then, the sheet guide angle with respect to the extension surface in the fixing unit direction is guided to be smaller than that of the first guide. For this reason, the second recording medium is peeled from the endless belt more slowly than the first recording medium guided by the first guide, at least while the tip portion is guided by the second guide.

  In addition, a pressing portion is provided at a position in the middle of the peeling direction between the first guide and the second guide to suppress the second recording medium guided by the second guide from floating. For this reason, even when the leading end of the second recording medium is guided to the fixing unit and the leading end further moves in the peeling direction, the pressing portion suppresses the floating of the second recording medium. It is possible to suppress the recording medium from being suddenly separated from the endless belt. Therefore, in the present invention, the stiff second recording medium can be prevented from being suddenly peeled off from the endless belt throughout the entire conveying process, and peeling discharge can be satisfactorily suppressed.

  On the other hand, the pressing portion does not protrude from the surface of the first guide, and does not hinder the guidance of the first recording medium by the first guide. The second guide is formed on the first guide leaving both ends of the first width. Therefore, the first recording medium is favorably guided to the fixing unit by the first guide. If only the stripping discharge is taken into consideration, the first guide may be integrally formed with the same inclination as the second guide, and a pressing portion may be provided at a location corresponding to the second width. In this case, the image may be distorted due to the pressing portion coming into contact with the image forming area of the first recording medium. On the other hand, in the present invention, since the pressing portion does not exist on the surface of the first guide, image formation on the first recording medium can be favorably performed without being affected by the pressing portion.

  In the present invention, the second guide may be integrally or separately connected to the second guide on the side away from the endless belt, and the inclination of the first guide may be larger than the inclination angle of the first guide with respect to the extended surface. An auxiliary guide for guiding the second recording medium to the fixing unit at a corner may be further provided. In this case, the recording medium conveyed by the second guide so that the paper guide angle in the fixing unit direction is smaller than that of the first guide passes through the portion facing the pressing portion, and then the second guide guides the first medium by the auxiliary guide. Since the guide can be guided to the fixing unit at an inclination angle larger than that of the first guide, the second recording medium is favorably guided toward the fixing unit in the same manner as the first recording medium guided by the first guide. be able to. In this case, the tip of the second recording medium moves along the large inclination angle when approaching the auxiliary guide, but the portion of the endless belt side of the pressing portion of the second recording medium is An increase in the inclination angle is suppressed by the pressing portion. For this reason, as described above, it is possible to suppress the second recording medium from being suddenly separated from the endless belt.

  Further, the end surface on the extension surface side of the pressing portion may abut on the surface of the second recording medium conveyed along the extension surface that does not abut on the endless belt. In this case, the second recording medium is conveyed along the extension surface (extension surface of the recording medium conveyance surface by the endless belt) at least on the endless belt side of the pressing portion. Therefore, in that case, the peeling discharge during the image formation of the second recording medium can be more effectively suppressed.

  The pressing portion protrudes from both side surfaces in the width direction of the dent or notch portion constituting the second guide and contacts the surface of the second recording medium that does not contact the endless belt. May be. In this case, the structure of the apparatus can be further simplified by projecting the pressing portion on the side surface of the dent or notch.

  In this case, the pressing portion may be a roller that contacts the outside of the image forming area of the second recording medium and rotates around the rotation axis in the width direction. In that case, since the pressing portion is a roller that rotates about the rotation axis in the width direction, it does not become a resistance to the conveyance of the second recording medium, and the pressing portion also contacts the outside of the image forming area. An image can be formed more satisfactorily on the second recording medium.

  Further, the pressing portion may be a star wheel that rotates around the rotation axis in the width direction and has a protrusion on the outer periphery. In that case, there is no possibility of disturbing the image even if it is brought into contact with the inside of the image forming area of the second recording medium, the peeling discharge can be more reliably suppressed, and the image formation on the second recording medium can be performed. It can be done well.

  Further, the pressing portion has an inclined surface that protrudes from both side surfaces in the width direction of the dent or notch portion constituting the second guide and contacts the edge in the width direction of the second recording medium. There may be. That is, for example, the pressing portion protrudes from both side surfaces in the width direction of the recess or notch portion constituting the second guide, and is an inclined surface inclined in the peeling direction toward the center in the width direction of the both side surfaces. It may have. In this case, there is no possibility of disturbing the image formed to the vicinity of the edge even if it is brought into contact with the edge in the width direction of the second recording medium, the peeling discharge can be reliably suppressed, and the second recording It is also possible to satisfactorily form an image on a medium.

1 is a central sectional view schematically showing a configuration of an image forming apparatus according to an embodiment. FIG. 3 is a perspective view of the sheet guide mechanism of the image forming apparatus as seen from the right front side together with a fixing device and a belt unit. FIG. 3 is a cross-sectional view illustrating the configuration of the paper guide mechanism, the fixing device, and the belt unit. FIG. 4 is an enlarged view of a portion A in FIG. 3 illustrating the configuration of the paper guide mechanism. It is the side view and perspective view showing the structure of the paper guide mechanism of other embodiment. It is the side view and perspective view showing the structure of the paper guide mechanism of other embodiment. FIG. 10 is a partial view illustrating a configuration of a paper guide mechanism of still another embodiment.

[Schematic configuration of image forming apparatus]
Next, embodiments of the present invention will be described with reference to the drawings. In this embodiment, the image forming apparatus according to the present invention is applied to an electrophotographic image forming apparatus. FIG. 1 is a central sectional view schematically showing a configuration of an image forming apparatus 1 according to the present embodiment. In the following description, the left side in FIG.

  As shown in FIG. 1, an image forming unit 2 (an example of an image forming unit) that forms an image on a sheet or an OHP sheet (hereinafter referred to as a sheet P) as an example of a recording medium includes four process cartridges 3K and 3Y. , 3M, 3C, exposure unit 4, fixing unit 5 (an example of fixing means), belt unit 10 and the like. In the present embodiment, the image forming unit 2 includes four types of four process cartridges 3K, 3Y, 3M, and 3C corresponding to toners (developers) of four colors of black, yellow, magenta, and cyan. A direct tandem method in which a toner image (developer image) is superimposed on the paper P to form a color image on the paper P is employed.

  Of the plurality of sheets P placed on the sheet feeding cassette 6 mounted below the image forming unit 2, the sheet P positioned at the top in the stacking direction picked up by the sheet feeding mechanism (feeder unit) 7 is After the paper dust is removed by the paper dust removing roller 8, it is conveyed to the registration roller 9. The registration roller 9 includes a driving roller 9A and a pinch roller 9B, corrects the skew of the paper P, and sends it to the belt unit 10 at a predetermined timing. The four process cartridges 3K and the like are arranged in series in the order of the process cartridges 3K, 3Y, 3M, and 3C from the upstream along the conveyance direction of the sheet P on the sheet conveyance surface side of the belt unit 10.

  For this reason, four types of toner images are sequentially transferred onto the paper P conveyed on the belt unit 10, and the toner images that have been transferred onto the paper P are heated by the fixing device 5 to be paper Fix to P. Then, the paper P discharged from the fixing device 5 is turned upward, and then discharged to a paper discharge tray 1A provided on the upper end surface side of the image forming apparatus 1.

  Each process cartridge 3K, 3Y, 3M, 3C houses a photosensitive drum 3A on which a toner image is carried, a charger (not shown) for charging the photosensitive drum 3A, and the like. Then, after exposing the charged photosensitive drum 3A with the exposure device 4 to form an electrostatic latent image on the outer peripheral surface of the photosensitive drum 3A, when toner is supplied to the photosensitive drum 3A, the outer periphery of the photosensitive drum 3A is A toner image is carried (formed) on the surface, and the toner image is transferred to the paper P.

  The fixing device 5 is also provided with a heating roller 5A for heating the toner to fix the toner image on the paper P, and a heating roller 5A disposed on the opposite side of the heating roller 5A across the conveyed paper P. And a pressure roller 5B that is pressed against the 5A side.

  As described above, the belt unit 10 is disposed at a position facing the photosensitive drums 3A of the four process cartridges 3K, 3Y, 3M, and 3C, and conveys the paper P. Specifically, the belt unit 10 includes a drive roller 12A and a driven roller 12B having a rotation axis parallel to the rotation axis of the photosensitive drum 3A, and a transfer conveyance belt provided between the drive roller 12A and the driven roller 12B. 12C (an example of an endless belt) or the like, and the paper P is transported in a state of being placed (adsorbed) on the transfer transport belt 12C. The driving roller 12A receives power from a motor (not shown) provided in the apparatus main body (not shown) and rotates the transfer conveyance belt 12C. The driven roller 12B is driven by the transfer conveyance belt 12C. Along with the rotation, it rotates following the drive roller 12A.

  Further, the tensioning surface of the transfer conveyance belt 12C facing the photosensitive drums 3A of the process cartridges 3K, 3Y, 3M, and 3C is a planar conveyance surface that conveys the paper P in the transfer conveyance belt 12C. Yes. The transport surface does not necessarily need to be horizontal and may be slightly inclined, but in the present embodiment, substantially coincides with the horizontal plane. Further, a toner image carried on the photosensitive drum 3A by energizing a certain transfer current at a position of the belt unit 10 facing each photosensitive drum 3A across the semiconductive transfer conveyance belt 12C. A transfer roller 12E for transferring the toner image onto the paper P is provided.

  By the way, the above-mentioned four process cartridges 3K, 3Y, 3M, 3C and the belt unit 10 are detachably attached to the apparatus main body (main body frame) covered with the casing 1C constituting the appearance design surface. . The top cover 1F provided with the paper discharge tray 1A in the housing 1C is assembled to the housing 1C so as to be swingable (openable / closable). By opening the top cover 1F upward, The two process cartridges 3K, 3Y, 3M, and 3C can be exchanged.

  Further, a part of the front cover 1G provided in front of the housing 1C is assembled as a manual feed tray 60 so as to be swingable (openable / closable), and the manual feed tray 60 is opened as indicated by a two-dot chain line. Thus, the paper P can be supplied to the registration rollers 9 from the front of the apparatus without using the paper feed cassette 6. Further, a rear cover 1H is attached to the rear of the housing 1C so as to be swingable (openable / closable). By opening the rear cover 1H as indicated by a two-dot chain line, the paper P that has passed through the fixing device 5 is provided in the apparatus. Can be discharged to the rear. When an image is formed on a stiff paper P such as a postcard, the user supplies the paper P by opening the manual feed tray 60 and the rear cover 1H in order to prevent the paper P from being greatly bent. And often discharge.

  Although not shown, each of the paper feed cassette 6 and the manual feed tray 60 includes a pair of paper guides that regulate the position of the paper P from both sides in the width direction orthogonal to the transport direction. This is a so-called center register that moves symmetrically with respect to the center in the width direction. For this reason, the center position of the paper P conveyed from the paper feed cassette 6 or the manual feed tray 60 to the belt unit 10 via the registration rollers 9 is constant regardless of its size.

[Details of paper guide mechanism]
The following paper guide mechanism 20 (an example of guide means) is provided on the transport path of the paper P from the transfer transport belt 12 </ b> C downstream of the process cartridge 3 </ b> C to the fixing device 5. Hereinafter, the configuration of the sheet guide mechanism 20 will be described.

  FIG. 2 is a perspective view of the paper guide mechanism 20 as viewed from the front right side together with the fixing device 5 and the belt unit 10, and FIG. 3 is a central view showing the configuration of the paper guide mechanism 20, the fixing device 5 and the belt unit 10. It is sectional drawing. As shown in FIG. 2, the belt unit 10 includes a belt unit frame set 13 that supports the driving roller 12A, the driven roller 12B, and the transfer roller 12E from both sides in the axial direction. In the belt unit frame set 13, two left and right side frames are connected to each other to form a frame shape that is thin in the vertical direction and has a substantially rectangular shape in plan view. As shown in FIG. 3, a sheet guide mechanism 20 including a first chute portion 21 and a second chute portion 22 is provided between the belt unit 10 and the fixing device 5.

  FIG. 4 is an enlarged view of a portion A in FIG. 3 showing the configuration of the paper guide mechanism 20 in detail. As shown in FIG. 4, the nip portion between the heating roller 5 </ b> A and the pressure roller 5 </ b> B of the fixing device 5 is provided at a position offset in the peeling direction of the paper P from the extended surface of the transport surface. This is due to the following circumstances.

  That is, in this type of image forming apparatus 1, the conveyance speed of the paper P by the heating roller 5A and the pressure roller 5B may be made smaller than the conveyance speed of the paper P by the transfer conveyance belt 12C. This is to suppress the occurrence of so-called color misregistration caused by the paper P during image formation being pulled by the heating roller 5A and the pressure roller 5B. In such a case, the sheet P may be bent in the middle from the surface of the transfer conveyance belt 12C to the nip portion between the heating roller 5A and the pressure roller 5B, but the fixing device 5 is offset as described above. This is because the conveyance path of the paper P is curved in advance, and the paper P is stably bent in the bending direction.

  The first chute unit 21 is a sheet P1 (first recording target) as a general high-quality sheet of A4 size or the like among the sheets P from the immediate rear of the driving roller 12A and from the lower side of the conveying surface toward the nip portion. A guide surface 21A (an example of a first guide) for guiding an example of a medium (see FIG. 4) to the nip portion is provided. As shown in FIG. 2, a concave portion 21B is formed in the guide surface 21A in the center in the width direction over the width corresponding to the length of the short side of the postcard along the paper conveyance direction, and the bottom surface of the concave portion 21B. 21C (an example of a 2nd guide) is comprised by the horizontal plane shape lower than the extension surface of the said conveyance surface. Further, cylindrical rollers 21F (an example of a pressing portion) that are rotatable about the central axis along the width direction protrude from the side surfaces 21E on both sides of the recess 21B. As shown in FIG. 4, the pair of rollers 21 </ b> F is formed in a circular shape that is in contact with the extension surface and the guide surface 21 </ b> A at the same time in a side view, and the bottom surface 21 </ b> C is directed rearward from the bottom to a position facing the roller 21 </ b> F. It extends.

  The second chute 22 extends from below the roller 21F and the bottom surface 21C toward the nip portion between the heating roller 5A and the pressure roller 5B, and among the sheets P, a sheet P2 such as a postcard (an example of a second recording medium) ) Guide surface 22A (an example of an auxiliary guide). That is, as described above, the recess 21B has a width corresponding to the length of the short side of the postcard and is provided at the center in the width direction of the transfer conveyance belt 12C. A sheet P2 such as a postcard passes inside the recess 21B. Further, both ends in the width direction are further conveyed while being in contact with the lower end surface of the roller 21F, and the leading end comes into contact with the guide surface 22A. The guide surface 22A guides such paper P2 to the nip portion.

  Since the paper P1 as a general high quality paper such as A4 size, legal size, letter size, etc. is larger than the postcard on both sides in the width direction, both ends in the width direction are guided to the guide surface 21A as described above, and It is conveyed to the nip part. At this time, as described above, since the roller 21F does not protrude in the conveyance path of the paper P1, the paper P1 is well guided to the fixing device 5.

[Effects of the embodiment and modifications thereof]
As described above, in the present embodiment, the paper P2, which is strong like a postcard, is not guided to the nip portion along the guide surface 21A, but is conveyed as it is along the extended surface. It is guided to the nip portion by the guide surface 22A. Also, when the leading edge of the paper P2 is guided by the guide surface 22A and rises, the rollers 21F suppress the floating of the paper P2. For this reason, in this embodiment, it is possible to suppress the paper P2 from being suddenly peeled off from the transfer conveyance belt 12C, and to prevent the image formed on the paper P2 from being disturbed by the peeling discharge.

  In particular, when an image is formed on both sides of the postcard by opening the manual feed tray 60 and inserting a postcard as the paper P2 twice, the postcard has the first side as the center of the arc when forming the second side image. Therefore, peeling discharge is more likely to occur. On the other hand, in the present embodiment, it is possible to suppress the paper P2 from being suddenly peeled off from the transfer conveyance belt 12C as described above. Can be suppressed.

  Furthermore, in the present embodiment, by rotating the roller 21F, it is possible to satisfactorily suppress resistance from being added to the conveyance while suppressing the floating of the paper P2. Moreover, since the roller 21F is provided on the side surface 21E of the recess 21B, the configuration of the apparatus can be further simplified.

  In addition, this invention is not limited to the said embodiment at all, It can implement with a various form in the range which does not deviate from the summary of this invention. For example, in the above-described embodiment, the guide surface 21A of the first chute portion 21 is configured as a first guide for guiding a sheet P1 as general high-quality paper of A4 size or the like, and the center of the guide surface 21A in the width direction is configured. A concave portion 21B is formed in the second portion to constitute a second guide for guiding the paper P2 such as a postcard. That is, the bottom surface 21C of the recess 21B is configured to have a horizontal flat surface lower than the flat conveyance surface for conveying the paper P in the transfer conveyance belt 12C, and the paper P2 such as a postcard conveyed along the conveyance surface. However, instead of the recess 21B, for example, by cutting out the center in the width direction of the guide surface 21A, the sheet P2 is directly moved along the transport surface in the horizontal direction. You may comprise as a 1st guide for the guidance for making it convey to. However, when the concave portion 21B is formed and the bottom surface 21C of the concave portion 21B is configured as the first guide, for example, even when the leading edge of the paper P2 is curled downward, the leading edge is It can be received on the surface of the bottom surface 21 </ b> C and smoothly guided to the guide surface 22 </ b> A of the second chute portion 22. Further, when the sheet P2 is detached from the transfer conveyance belt 12C, the rear end of the sheet P2 can be received by the surface of the bottom surface 21C and can be suppressed rapidly, and the guide surface 22A of the second chute 22 can be suppressed. Can be guided smoothly. Further, if the bottom surface 21C is configured so that the edge of the transfer / conveying belt 12C side is inclined or rounded so that the leading edge of the paper P2 does not collide, the bottom surface 21C is not necessarily more than the conveying surface. It is not necessary to form it low, and it may be formed so as not to be horizontal but to be slightly inclined so that the rear end side (fixer 5 side) is high.

  Further, the first chute part and the second chute part may be swingable. FIG. 5A is a side view schematically showing the configuration of the sheet guide mechanism 120 adopting such a configuration, and FIG. 5B is a perspective view thereof.

  As shown in FIG. 5, in the paper guide mechanism 120, the first chute portion 121 including the guide surface 121A, the concave portion 121B, the bottom surface 121C, the side surface 121E, and the roller 121F is the same as the first chute portion 21 of the above embodiment. , And can swing around a shaft 121P provided at the front end. Similarly to the second chute portion 22 of the above-described embodiment, the second chute portion 122 provided with the guide surface 122A can swing around a shaft 122P provided at the front end (lower end). The first chute portion 121 is biased upward by a compression coil spring 126, and the second chute portion 122 is biased upward by a compression coil spring 127.

  In the sheet guide mechanism 120 configured as described above, the first chute portion 121 and the second chute portion 122 swing against the urging force of the compression coil springs 126 and 127 according to the strength of the waist of the paper P. . Accordingly, the stiff paper P can be smoothly guided to the fixing device 5.

  Further, like the paper guide mechanism 220 schematically shown in the side view of FIG. 6A and the perspective view of FIG. 6B, the guide surface 121A, the recess 121B, the bottom surface 121C, the side surface 121E, the roller, and the like. The 121F and the guide surface 122A may be provided in the integrated chute portion 223. The chute 223 can also swing around a shaft 223P provided at the front end, and is urged upward by a compression coil spring 227. In the paper guide mechanism 220, substantially the same effect as that of the paper guide mechanism 120 can be obtained with a simpler configuration.

  In addition to the rollers 21F and the like, various forms are conceivable as the pressing portion. For example, instead of the roller 21F, a cylindrical projection that does not rotate may be provided. As a protrusion, as shown in FIG. 7A, it is conceivable that a protrusion 321F having an inclined lower surface 321G protrudes from the side surface 21E of the recess 21B. That is, the lower surface 321G is inclined upward toward the center in the width direction of the pair of side surfaces 21E. For this reason, as shown in FIG. 7A, the lower surface 321G abuts only on both edges in the width direction of the paper P2, and does not abut on the surface of the paper P2. In the roller 21F and the like, it is necessary to provide the roller 21F outside the image forming area of the paper P2. However, if such a protrusion 321F is used, an image can be formed on the entire surface of the paper P2.

  Further, as shown in FIG. 7B, a cone-shaped roller 421F having a small end face near the center in the width direction may be rotatably provided on the pair of side surfaces 21E. In that case, in addition to the effect that an image can be formed on the entire surface of the paper P2, as described above, the roller 421F rotates, so that it is possible to more effectively suppress resistance applied to the conveyance of the paper P2.

  Further, the pressing portion may be a star wheel that rotates around the rotation axis in the width direction and has a protrusion on the outer periphery. In that case, even if the star wheel contacts the image forming area of the paper P2, there is no possibility of disturbing the image, and the peeling discharge can be more reliably suppressed and the image formation on the paper P2 can be performed well.

  In each of the above embodiments, the width of the concave portion 21B or the like is a width through which a postcard can pass. However, this width may be a width corresponding to a relatively stiff recording medium such as a business card or a greeting card. . This type of width is appropriately set in advance at the time of designing according to the lifestyle of the country and region where the image forming apparatus is used and the size of the image forming apparatus itself. Further, the second chute portion 22 and the like are not necessarily provided, and can be omitted when the diameter of the pressure roller 5B is sufficiently large and the leading end of the paper P2 is wound from below. Also in this case, since the paper P2 is disposed almost horizontally by the roller 21F on the upstream side in the paper transport direction from the roller 21F, the peeling discharge can be suppressed satisfactorily.

  Further, in the embodiment shown in FIGS. 1 to 4, the first chute portion 21 and the second chute portion 22 can be retracted downward from the illustrated position, similarly to the embodiments shown in FIG. 5. Of course, it may be configured to be swingable, and by being provided with a compression coil spring similar to the compression coil springs 126 and 127, it may always be elastically held at the illustrated position.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 1H ... Rear cover 2 ... Image forming part 3A ... Photosensitive drum 5 ... Fixing device 5A ... Heating roller 5B ... Pressure roller 10 ... Belt unit 12C ... Transfer conveyance belt 12E ... Transfer roller 20, 120, 220 ... Sheet guide mechanism 21, 121 ... first chute portion 21A, 22A, 121A, 122A ... guide surface 21B, 121B ... concave portion 21C, 121C ... bottom surface 21E, 121E ... side surface 21F, 121F, 421F ... roller 22, 122 ... second chute Portion 60 ... Manual feed tray 121P, 122P, 223P ... Shaft 126, 127, 227 ... Compression coil spring 223 ... Chute 321F ... Projection 321G ... Bottom surface P, P1, P2 ... Paper

Claims (7)

An endless belt that conveys a recording medium by being laid between a plurality of rollers and driven to rotate;
An image forming unit that forms an image by electrophotography using a transfer current on a recording medium conveyed by the endless belt;
The image formed on the recording medium by the image forming means is heat-fixed with respect to the recording surface of the recording medium by the endless belt, which is offset from the extended surface of the conveying surface in the peeling direction of the recording medium. Fixing means for
Guide means for guiding the recording medium on which the image is formed by the image forming means to the fixing means;
With
The guide means includes
A first guide that is provided to be inclined in the fixing unit direction with respect to the extended surface and guides a first recording medium having a first width that is perpendicular to the conveying direction of the endless belt to the fixing unit. When,
The first guide is configured to be recessed or cut out along the recording medium conveyance direction, leaving at least both ends of the first width, and has a second width smaller than the first width. A second guide for guiding the second recording medium such that a sheet guide angle in the fixing unit direction with respect to the extended surface is smaller than that of the first guide;
The first guide is provided at an intermediate position in the peeling direction between the first guide and the second guide, suppresses floating of the second recording medium guided by the second guide, and the first guide. A pressing part that does not protrude from the surface of
An image forming apparatus comprising: The second guide is connected to the second guide on the side away from the endless belt or integrally with the second guide, or at a tilt angle larger than the tilt angle with respect to the extended surface of the first guide. An auxiliary guide for guiding the medium to the fixing unit;
The image forming apparatus according to claim 1, further comprising:   2. The end surface of the pressing portion on the side of the extension surface abuts on a surface of the second recording medium conveyed along the extension surface that does not abut on the endless belt. The image forming apparatus according to 2.   The pressing portion protrudes from both side surfaces in the width direction of the dent or notch portion constituting the second guide and comes into contact with a surface of the second recording medium that does not contact the endless belt. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   5. The image forming apparatus according to claim 4, wherein the pressing portion is a roller that is in contact with an outer side of an image forming area of the second recording medium and rotates about a rotation axis in the width direction.   The image forming apparatus according to claim 1, wherein the pressing portion is a star wheel that rotates around the rotation axis in the width direction and has a protrusion on an outer periphery.   The pressing portion has an inclined surface that protrudes from both side surfaces in the width direction of the recess or notch portion constituting the second guide and abuts against an edge in the width direction of the second recording medium. The image forming apparatus according to any one of claims 1 to 3.

Images