JP6287736B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including a transfer device that transfers a toner image formed on an image carrier onto a sheet.

  In an image forming apparatus such as a copying machine, a printer, or a multifunction machine, a toner image formed on an image carrier is transferred onto a sheet by a transfer device. In the transfer device, the toner image is transferred to the paper by guiding the paper along a guide to a transfer nip formed between the image carrier and the transfer member, and applying a transfer bias to the transfer member.

  The sheet is guided by a guide so as to be as close as possible to the image carrier before the transfer bias is applied in order to suppress toner scattering due to pre-transfer and image defects due to abnormal discharge. However, if thick paper such as postcards is guided by a guide fixed to the plain paper, the load on the paper from the guide increases due to the thickness and stiffness of the paper, and the transport speed is slow. As a result, the magnification is changed or an image defect such as a void is generated.

  In order to prevent the occurrence of image defects due to such a fixed guide, an image forming apparatus configured to displace the guide is disclosed. For example, Patent Document 1 discloses an image forming apparatus including a rigid guide that is rotatably provided so that one end thereof is elastically biased in the direction of an image carrier. Further, Patent Document 2 includes a guide that is supported so that the end portion on the image carrier side is bent, and in the case of thin paper, the end portion is in close contact with the image carrier without bending, and in the case of thick paper, the end portion is bent. A configured image forming apparatus is disclosed. Patent Document 3 discloses an image forming apparatus including a buffer member that protrudes in the direction of the image carrier from the lower surface of a flexible guide. Further, Patent Document 4 has a flexible guide that can swing in the direction of the image carrier, and is configured to restrict the swing of the guide in the direction opposite to the image carrier by a protruding portion. An image forming apparatus is disclosed.

Japanese Patent Laid-Open No. 06-130825 JP-A-2005-128482 JP 2008-26810 A JP 2012-203227 A

  However, in the image forming apparatus described in Patent Document 1, it is difficult to adjust the urging force with respect to sheets having different thicknesses, widths, and rigidity. Therefore, image defects such as voids cannot be suppressed. In order to suppress such image defects, it is necessary to attach an expensive low friction member, which increases the cost. Further, in the image forming apparatus described in Patent Document 2, horizontal stripes, character blurring, and the like are likely to occur due to vibration when the trailing edge of the paper is separated from the guide. In the image forming apparatus described in Patent Document 3, In addition, friction between the buffer member and the paper may occur, and the back surface of the paper may become dirty or wear of the buffer member may occur. Furthermore, in the image forming apparatus described in Patent Document 4, the height at which the trailing edge of the sheet is separated from the guide varies depending on the rigidity of the sheet, and image defects are likely to occur at the trailing edge of the sheet.

  In view of the above circumstances, an object of the present invention is to provide an image forming apparatus including a guide capable of guiding sheets having different thicknesses and widths to a transfer nip with an appropriate load.

  In order to solve the above problems, an image forming apparatus of the present invention forms a transfer nip between an image carrier and a transfer member that transfers a toner image from the image carrier to a sheet in the transfer nip, A guide member that guides the paper along a transport path of the paper toward the transfer nip, wherein the guide member is a guide plate formed of an elastic thin material; and And a plurality of elastic members arranged along a paper width direction intersecting with a paper conveyance direction and supporting the guide plate so as to be displaceable in a direction away from the image carrier.

  By adopting such a configuration, the guide plate is partially supported with a small load, so that the guide plate is partially elastically deformed according to the width and thickness of the paper. Therefore, on the plain paper with a small thickness, the guide plate is hardly displaced, and pre-transfer can be suppressed to prevent image defects due to toner scattering and abnormal discharge. On the other hand, for thick paper such as postcards, the guide plate is displaced in a direction away from the image carrier according to the width of the thick paper, so that no conveyance load is applied from the guide plate to the paper. Can be prevented.

  In the image forming apparatus according to the aspect of the invention, the elastic member may be arranged at least in one portion other than both end portions in the width direction to support the guide plate.

  By adopting such a configuration, the distance between the elastic members is shortened, the load on the guide plate is dispersed and supported, and the guide plate can be displaced in accordance with the width of the paper. It is possible to prevent image defects even on paper having a narrow width and a large thickness.

  In the image forming apparatus according to the aspect of the invention, the guide plate is separated from the image carrier from a main body portion extending in the direction of the image carrier along the transport direction and a downstream end of the main body portion in the transport direction. And a ridge line portion where the main body portion and the inclined portion intersect with each other is supported by the elastic member so as to be closest to the image carrier. Also good.

  By adopting such a configuration, it is possible to suppress vibrations that occur when the trailing edge of the sheet moves away from the guide plate, and it is possible to prevent image defects such as horizontal stripes, toner scattering, and character blurring.

  In the image forming apparatus according to the aspect of the invention, the guide plate is configured such that a ridge line portion where the main body portion and the inclined portion intersect is closest to the image carrier and the inclined portion is inclined in a direction away from the image carrier. It is good also as being supported by the said elastic member so that it may displace while maintaining.

  By adopting such a configuration, even when the guide plate is displaced in a direction away from the image carrier due to thick paper such as a postcard, vibration generated when the rear end of the paper is separated from the guide plate can be suppressed. Image defects such as horizontal stripes, toner scattering, and character blur can be prevented.

  In the image forming apparatus according to the aspect of the invention, the guide member may include a displacement amount regulating member that regulates a displacement amount of the guide plate in a direction away from the image carrier.

  By adopting such a configuration, it is possible to prevent a situation in which the guide plate is displaced beyond a necessary amount and accidentally contacts the transfer roller.

  In the image forming apparatus according to the aspect of the invention, the displacement amount regulating member may be configured such that the maximum displacement amount of the guide plate in a specific small-size cardboard passing region is larger than the maximum displacement amount of the guide plate in the other sheet passing regions. It may be characterized by being formed to be large.

  By adopting such a configuration, the load on the small-sized cardboard (such as postcards) from the guide plate is reduced, so image defects such as change in magnification and dropout when using small-sized cardboard are eliminated. Can be prevented.

  In the image forming apparatus according to the aspect of the invention, the guide member may include a twist restriction portion that restricts the guide plate from twisting.

  By adopting such a configuration, it is possible to easily handle a paper jam occurring near the transfer nip.

  According to the present invention, papers having different thicknesses and widths can be guided to the transfer nip with an appropriate load. Therefore, in plain paper, pre-transfer, toner scattering, and image defects due to abnormal discharge are suppressed, and in thick paper such as postcards. Can suppress image defects such as a change in magnification and voids.

1 is a schematic diagram illustrating an outline of a printer according to an embodiment of the present invention. FIG. 3 is a front view illustrating a configuration between a registration roller pair and a transfer nip in the printer according to the embodiment of the present invention. FIG. 3A is a front view showing a guide member in the printer according to one embodiment of the present invention, and FIG. 3B is a cross-sectional view taken along the line AA in FIG. 4 (A) and 4 (B) are front views showing the sheet conveying operation in the printer according to the embodiment of the present invention. FIG. 4 (A) is a plain sheet conveying operation, and FIG. B) shows the postcard transport operation. 5A and 5B are a cross-sectional view taken along line AA in FIG. 4A and a cross-sectional view taken along line BB in FIG. 4B, respectively. 6A and 6B are front views showing a state in which the rear end of the paper leaves the guide plate in the printer according to the embodiment of the present invention, and FIG. FIG. 6B shows the case of a postcard. 7A and 7B are views showing a modification of the guide unit in the printer according to the embodiment of the present invention. FIG. 7A is a front view, and FIG. It is AA sectional drawing of FIG. 7 (A). 8A and 8B are diagrams showing another example of the guide unit in the printer according to the embodiment of the present invention. FIG. 7A is a front view, and FIG. Is a side view seen from the right.

  Hereinafter, an image forming apparatus according to an embodiment of the present disclosure will be described with reference to the drawings.

  First, the main configuration of the entire printer 1 (image forming apparatus) will be described with reference to FIG. FIG. 1 is a schematic diagram showing an outline of a printer according to an embodiment of the present invention. Hereinafter, the front side in FIG. 1 is the front side (front side) of the color printer 1, and the left and right directions will be described with reference to the direction viewed from the front of the printer 1.

  The printer 1 includes a box-shaped printer main body 2. A paper feed cassette 3 is provided at the lower part of the printer main body 2, and a paper feed unit 4 for feeding paper P from the paper feed cassette and a registration roller pair 5 are provided at the upper left of the paper feed cassette. ing. A paper discharge tray 6 is provided at the top of the printer body 2. Inside the printer main body 2, a toner container 7 containing toner is disposed above and an exposure device 8 including a laser scanning unit (LSU). An image forming unit 10 is provided below the exposure device 8.

  The image forming unit 10 is rotatably provided with a photosensitive drum 11 as an image carrier. Around the photosensitive drum 11, a charging device 12, a developing device 13, a transfer roller 14, a static eliminating device 15, and a cleaning device 16 are sequentially arranged along the rotation direction of the photosensitive drum 11. . Further, a fixing device 17 is provided on the right side of the image forming unit 10, and a paper discharge unit 18 facing the paper discharge tray 6 is provided above the fixing device 17.

  Further, inside the printer main body 2, the paper feed unit 4 passes through a registration roller pair 5, a transfer nip 19 formed between the photosensitive drum 11 and the transfer roller 14, and a fixing device 17. A paper transport path 20 toward the paper discharge unit 18 is provided. The conveyance path 20 branches to a reverse path 21 on the downstream side of the fixing device 17. The reverse path 21 joins the transport path 20 on the downstream side of the paper feeding unit 4.

  Next, an image forming operation of the printer 1 having such a configuration will be described. When image data is input from a computer or the like connected to the printer 1, an image forming operation is executed as follows.

  First, after the surface of the photosensitive drum 11 is charged by the charging device 12, exposure corresponding to image data is performed on the photosensitive drum 11 by laser light from the exposure device 8 (see the dotted line P in FIG. 1). Then, an electrostatic latent image is formed on the surface of the photosensitive drum 11. The electrostatic latent image is developed into a corresponding color toner image by the developing device 13.

  On the other hand, the paper taken out from the paper feed cassette 3 or the manual feed tray (not shown) by the paper feed unit 4 is synchronized with the above-described image forming operation by the registration roller pair 5 and then transferred along the transport path to the transfer nip. It is conveyed to 19. In the transfer nip 19, a transfer bias having a polarity opposite to the polarity of the toner is applied to the transfer roller 14, and the toner image on the photosensitive drum 11 is transferred to the sheet. The sheet on which the toner image has been transferred is separated from the photosensitive drum 11 by the static eliminator 15, transported downstream in the transport path 20, and enters the fixing device 17, where the toner image is fixed on the sheet. Is done. The paper on which the toner image is fixed is discharged from the paper discharge unit 18 onto the paper discharge tray 6. The toner remaining on the photosensitive drum 11 is removed by the cleaning device 16.

  Next, a configuration between the registration roller pair 5 and the transfer nip 19 will be described with reference to FIGS. 2, 3 </ b> A, and 3 </ b> B. 2 is a front view showing a configuration between the registration roller pair and the transfer nip, FIG. 3A is a front view showing a guide member, and FIG. 3B is a cross-sectional view taken along line AA in FIG. is there.

  As shown in FIG. 2, between the registration roller pair 5 and the transfer nip 19, a pre-transfer upper guide plate 31 and a pre-transfer lower guide plate 32 that form the transport path 20 are provided facing each other in the vertical direction. It has been. The pre-transfer upper guide plate 31 extends in the direction of the transfer nip 19 more than the pre-transfer lower guide plate 32, and is slightly convexly curved in an arc shape. The pre-transfer lower guide plate 32 is inclined upward from the registration roller pair 5 toward the transfer nip 19.

  Below the downstream end (right end) in the transport direction of the upper guide plate 31 before transfer, between the right end portion of the lower guide plate 32 before transfer and the transfer roller 14, the paper width direction orthogonal to the transport direction of the paper. A guide member 40 is provided so as to extend in the direction. The guide member 40 has a length slightly longer than the maximum sheet passing width (for example, A4 horizontal size) of the printer 1, and a support member 41 provided so as to extend in the sheet width direction orthogonal to the sheet conveying direction, It has the guide plate 42 which a back surface contacts, and the some elastic member 43 which supports the guide plate 42. FIG.

  As shown in FIG. 3A, the support member 41 has a channel-like shape with an open upper surface, and includes a left wall 41a and a right wall 41b (displacement amount regulating member) facing each other, and a bottom wall 41c. Have. The height of the left wall 41a is formed lower than the height of the right end portion of the pre-transfer lower guide plate 32. At a position near the upper end of the left wall 41a, a plurality of (for example, five) through-holes 41d penetrating in the left-right direction with a predetermined interval along the paper width direction and having a predetermined height are formed. Yes. The right wall 41b is formed lower than the left wall 41a.

  The guide plate 42 has a length slightly longer than the width (for example, A4 horizontal size) of the maximum width sheet of the printer 1 and extends slightly downward from the horizontally extending main body 42a and the right edge of the main body 42a. And an inclined portion 42b that is inclined. On the left edge of the main body portion 42a, a locking portion 42c extending in the left direction is formed at a position corresponding to the through hole 41d formed in the left wall 41a of the support member 41. The guide plate 42 is formed of a thin material that can be partially elastically deformed in the paper width direction. As such a material, for example, SUS (stainless steel) having a thickness of 0.1 mm or a resin can be used.

  The elastic member 43 is formed of a plurality of (for example, five) compression coil springs. As shown in FIG. 3B, both ends in the paper width direction are formed on the bottom wall 41c of the support member 41. It is arranged at equal intervals in a total of 5 places, 3 places between both ends.

  The elastic member 43 supports the guide plate 42 in a state where the engaging portions 42 c of the guide plate 42 are inserted at positions near the upper portions of the through holes 41 d of the support member 41. Note that the guide plate 42 is prevented from coming off in the through hole 41d of the support member 41 by, for example, bending the tip of the locking portion 42c. The guide plate 42 has a main body portion 42a that extends horizontally from the left wall 41a of the support member 41 to the right side of the right wall 41b above the opening of the support member 41, and an inclined portion 42b that extends to the right of the main body portion 42a. It is supported so as to incline downward from the edge toward the transfer nip 19. There is a gap between the main body 42 a and the right wall 41 b of the support member 41. Further, the guide plate 42 can move and swing downward in the through hole 41d until the main body portion 42a contacts the right wall 41b of the support member 41.

  As shown in FIG. 2, the guide plate 42 has a ridge line portion 42d where the main body portion 42a and the inclined portion 42b intersect with each other closest to the photosensitive drum 11, and the inclined portion 42b moves toward the right end. 11 is supported in a posture away from 11. Further, even when the guide plate 42 is displaced until it abuts against the right wall portion 41b of the support member 41, the ridge line portion 42d comes closest to the photosensitive drum 11, and the inclined portion 42b moves from the photosensitive drum 11 toward the right end. The attitude to leave is maintained.

  4A and 4B, FIG. 5A and FIG. 5B, FIG. 4A and FIG. 4B with respect to the sheet conveying operation from the registration roller pair 5 to the transfer nip 19 in the guide member 40 having the above configuration. This will be described with reference to FIG. 6 (A) and FIG. 6 (B). 4A is a front view illustrating the transport operation of plain paper, FIG. 4B is a front view illustrating the transport operation of the postcard, and FIG. 5A is a state of the guide plate when the plain paper is transported. 4A is a cross-sectional view taken along the line AA in FIG. 4A, and FIG. 5B is a cross-sectional view taken along the line BB in FIG. 4B showing a state of the guide plate when the postcard is conveyed. FIG. 6A is a front view showing how the rear end of plain paper leaves the guide plate, and FIG. 6B is a front view showing how the rear end of the postcard leaves the guide plate.

  As shown in FIG. 4A, when the A4-sized plain paper P1 is conveyed, the plain paper P1 passes from the lower guide plate 32 before transfer to above the guide plate 42 and hits the ridge line portion 42d of the guide plate 42. Then, it hits the surface of the photosensitive drum 11 and is conveyed to the transfer nip 19 as it is. Since the plain paper P1 is light and thin, the guide plate 42 hardly displaces as shown in FIG. When the rear end of the paper P1 moves away from the guide plate 42, as shown in FIG. 6A, the rear end of the paper P1 is photosensitive along the inclined portion 42b of the guide plate 42 (see the two-dot chain line). It is guided so as to gradually move away from the body drum 11.

  On the other hand, even when the postcard P2 is conveyed, as shown in FIG. 4B, it passes from the lower guide plate 32 before transfer to above the guide plate 42 and contacts the ridge line portion 42d of the guide plate 42 to the transfer nip 19. However, since the postcard P2 has high rigidity and is thick, the ridgeline portion 42d is pushed downward by the postcard P2. Then, as shown in FIG. 5B, the elastic member 43C disposed in the paper passing area of the postcard P2 is compressed more than the elastic member 43 in the other area, and the guide plate 42 bends downward. At this time, depending on the thickness of the postcard P <b> 2, the guide plate 42 bends downward until it contacts the right wall 41 b of the support member 41. When the rear end of the postcard P2 moves away from the guide plate 42, the guide plate 42 is biased upward by the elastic member 43. However, as shown in FIG. 6B, the rear end is inclined by the guide plate 42. It is guided along the portion 42b (see the two-dot chain line) so as to gradually move away from the photosensitive drum 11. Then, after the rear end of the postcard P2 passes through the ridge line portion 42d of the guide plate 42, the guide plate 42 returns to the normal position or almost the normal position.

  As described above, in the printer 1 according to the present embodiment, the load of the guide plate 42 that is elastically deformable in the paper width direction is dispersed and supported by the plurality of elastic members 43, so the thickness of the conveyed paper Depending on the sheath rigidity, the guide plate 42 is partially displaced in the width direction away from the photosensitive drum 11.

  In other words, in the case of plain paper having a small thickness and low rigidity, the guide plate 42 is transported to the transfer nip 19 along the surface of the photosensitive drum 11 with almost no displacement. And image defects such as baldness and white spots can be suppressed. On the other hand, in the case of a specific small size thick paper such as a postcard or the like having a large thickness and high rigidity, the paper passing area of the guide plate 42 is displaced downward, and passes through the transfer nip 19 without applying an excessive load to the paper. Therefore, it is possible to prevent a change in magnification and a dropout due to a conveyance load. The specific small-size cardboard includes a greeting card, a small-size envelope, and the like, and is not limited to a postcard.

  When the guide plate 42 is formed of a rigid material that cannot be elastically deformed, if the guide plate 42 is supported by a specific small-size cardboard so that the guide plate 42 is tilted properly, the guide plate 42 is tilted in the full-size cardboard. The angle increases, and the transfer nip 19 cannot be conveyed in an appropriate state.

  In the present embodiment, since the guide plate 42 is supported by the plurality of elastic members 43, the load of the guide plate 42 is supported in a more dispersed manner, and the guide plate 42 can be displaced according to the width of the paper. In addition, it is possible to prevent image defects even on a postcard or the like having a narrow width and a large thickness. In addition, by disposing the elastic member 43 in at least one place other than both ends of the guide plate 42, the guide plate 42 can be displaced according to the width of the sheet.

  Further, in the present embodiment, when the rear end of the paper is separated from the guide plate 42, the rear end is guided in a direction away from the photosensitive drum 11 along the inclined portion 42 from the ridge line portion 42 d of the guide plate 42. . Therefore, it is possible to suppress vibrations that occur when the paper leaves the guide plate 42, and to prevent occurrence of horizontal stripes, toner scattering, character blur, and the like.

  Furthermore, in the present embodiment, the downward displacement of the guide plate 42 is regulated by the right wall 41b of the support member 41, so that the guide plate 42 is displaced beyond a necessary amount and accidentally contacts the transfer roller 14. Can be prevented. Furthermore, when a thick paper such as a postcard is passed, it is possible to suppress a situation in which the guide plate 42 escapes too much (displaces beyond a necessary amount) and toner scattering occurs. Can be secured.

  In the present embodiment, as shown in FIG. 7, on the right wall 41 b of the support member 41, a specific small-size cardboard passing area W1 such as a postcard (hereinafter referred to as a postcard passing area W1 for convenience). A notch 41e having a predetermined depth from the upper end may be formed at a position corresponding to. By forming such a notch 41e, the displacement amount of the guide plate 42 is increased in the postcard paper passing area W1.

  When there is a section in which a sheet is transported by the transport force of only the transfer roller 14 such as a thick sheet having a short length and a narrow width, such as a postcard, the transport speed is increased by the load applied to the sheet from the guide member in this section. It tends to decline. For this reason, by increasing the amount of displacement of the guide plate 42 in the post-sheet passing area W1, the load applied to the paper from the guide plate 42 is reduced, so that a decrease in the conveyance speed is prevented, and a change in magnification or a dropout is prevented. Such image defects can be prevented.

  In the support member 41, the right wall 41b may not be provided at a position corresponding to the postcard paper passing area W1. Also in this case, the amount of displacement of the guide plate 42 in the postcard paper passing area W1 can be increased to prevent image defects such as a change in magnification and hollowing out.

  Next, a guide unit according to another example of the present invention will be described with reference to FIG. FIG. 8A is a front view of the guide portion, and FIG. 8B is a view of the guide portion as viewed from the right. The guide unit 40 includes a support member 41, a guide plate 42, and a plurality of elastic members 43 that support the guide plate 42.

  On the right side surface of the right wall 41b, the support member 41 is formed with a plate-like locking portion 41f that protrudes substantially horizontally in the right direction so as to extend in the paper width direction. The locking portion 41f may be partially formed along the paper width direction.

  The guide plate 42 includes a horizontally extending main body portion 42a, an inclined portion 42b inclined slightly downward from the right edge of the main body portion 42a, and a locking piece 42e inclined downward from the right edge of the inclined portion 42b. . As shown in FIG. 8B, the locking pieces 42e are formed at three locations near the center along the right edge of the inclined portion 42b. The guide plate 42 is supported by the elastic member 43 so that the tip of each locking piece 42e is positioned below the locking portion 41f of the support member 41.

  In the guide portion 40, when the guide plate 42 is about to be rolled up, the locking piece 42e is locked to the locking portion 41f of the support member 41 to prevent the guide plate 42 from rolling up. Therefore, for example, when a paper jam occurring near the transfer nip 19 is processed, it is possible to prevent the guide plate 42 from being caught by the paper and curling up, and the paper jam can be easily handled.

  Further, in the embodiment of the present invention, the case where the configuration of the present invention is applied to the printer 1 has been described. However, in another different embodiment, the present invention is applied to an image forming apparatus other than the printer 1 such as a copying machine, a facsimile machine, and a multifunction machine. You may apply the structure of invention.

  Furthermore, since the above description of the embodiment of the present invention describes a preferred embodiment of the image forming apparatus according to the present invention, there may be various technically preferable limitations. The technical scope of the present invention is not limited to these embodiments unless specifically described to limit the present invention. That is, the above-described components in the embodiment of the present invention can be appropriately replaced with existing components and the like, and various variations including combinations with other existing components are possible. The description of the embodiment of the present invention described above does not limit the contents of the invention described in the claims.

1 Printer (image forming device)
11 Photosensitive drum (image carrier)
14 Transfer roller (transfer member)
19 Transfer nip 40 Guide member 41b Right wall (displacement amount regulating member)
41f Locking part (dripping restriction part)
42 Guide plate 42a Body portion 42b Inclined portion 42d Ridge portion 42e Locking piece (turning restricting portion)
43 Elastic member

Claims (4)

A transfer nip formed between the image carrier and a transfer member for transferring a toner image from the image carrier to a sheet in the transfer nip;
A guide member that guides the paper along a transport path of the paper toward the transfer nip;
An image forming apparatus comprising:
The guide member is
A support member formed so as to extend in the paper width direction intersecting the paper conveyance direction;
A guide plate formed of a thin material having elasticity;
A plurality of elastic members disposed along the paper width direction and supporting the guide plate so as to be displaceable in a direction away from the image carrier;
Have
The support member has a shape with an open top surface, and includes one wall on the upstream side in the transport direction and the other wall on the downstream side in the transport direction and the bottom wall facing each other along the transport direction of the paper. a, the other wall is the formed height lower than one wall, wherein the one wall, and the through holes are formed in plural at predetermined intervals along the sheet width direction ,
The guide plate includes a main body that extends in the direction of the image carrier along the transport direction, an inclined portion that inclines in a direction away from the image carrier from a downstream end of the main body in the transport direction, A locking portion that can be inserted into the through hole is formed on the upstream edge of the main body portion in the transport direction, and a ridge line portion that intersects the main body portion and the inclined portion is formed on the image carrier. It is supported by the elastic member so as to be displaced while maintaining a posture in which the inclined portion is closest to and is inclined in a direction away from the image carrier,
The image forming apparatus, wherein the elastic member supports the guide plate by being arranged at equal intervals on at least one portion of the support member other than both ends in the sheet width direction on the bottom wall. .   The image forming apparatus according to claim 1, wherein the other wall of the support member functions as a displacement amount regulating member that regulates a displacement amount of the guide plate in a direction away from the image carrier. .   The displacement amount regulating member is formed such that the maximum displacement amount of the guide plate in a paper passing area of a specific small-sized cardboard is larger than the maximum displacement amount of the guide plate in another paper passing area. The image forming apparatus according to claim 2.   4. The image forming apparatus according to claim 1, wherein the guide member includes a curl regulation unit that regulates curl of the guide plate. 5.

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