Structure for adjusting a paper path gap using roller movement according to the thickness of paper

Abstract

An image forming apparatus includes: an image bearing member including a movable surface for holding a toner image; a transfer roller for forming a transfer nip between the transfer roller and the movable surface of the image bearing member, for performing a position movement in a direction intersecting the introduction direction of the print medium into the transfer nip corresponding to the thickness of the print medium, and for receiving a transfer bias voltage to transfer the toner image from the movable surface of the image bearing member to the print medium; and a movement guiding structure for guiding the print medium toward the transfer nip and for moving in synchronization with the position movement of the transfer roller to change the gap between the end portion of the movement guiding structure facing the image bearing member and the image bearing member.

Description

Technical Field

[0001] The present disclosure generally relates to a structure for adjusting a paper path gap using roller movement according to the thickness of paper. Background Art

[0002] An image forming apparatus prints an image on a print medium that is transported along a transport path by a transfer roller. For example, an electrophotographic image forming apparatus scans a photoconductor having a uniform electric potential to form an electrostatic latent image, and supplies toner to the electrostatic latent image to form a toner image on the photoconductor. The toner image is transferred to a print medium that is transported along the transport path. When the print medium passes through a fixing section, the toner image is fixed to the print medium by heat and pressure to become a permanent image.

[0003] An image forming apparatus includes a guiding structure that guides a print medium to be smoothly transported along a transport path. Considering manufacturing tolerances, transport of the print medium, or transfer of the toner image, the guiding structure has a certain gap with an adjacent component.

[0004] However, due to this gap, a step (or height difference) may occur, which may affect the transport path of the print medium. Summary of the Invention

[0005] According to an aspect of the present disclosure, an image forming apparatus includes: an image bearing member including a movable surface for including a toner image; a transfer roller for forming a transfer nip between the transfer roller and the movable surface of the image bearing member, for performing a position movement in a direction intersecting with an introduction direction of the print medium into the transfer nip corresponding to the thickness of the print medium, and for receiving a transfer bias voltage to transfer the toner image from the movable surface of the image bearing member to the print medium; and a movement guiding structure for guiding the print medium toward the transfer nip and for synchronously moving with the position movement of the transfer roller to change a gap between an end portion of the movement guiding structure facing the image bearing member and the image bearing member. Brief Description of the Drawings

[0006] Figure 1 is a configuration diagram of an example of an image forming apparatus according to an example.

[0007] Figure 2 is a view for explaining an operation of a transfer unit of an image forming apparatus according to an example.

[0008] Figure 3 is Figure 2 an enlarged view of part A of an example.

[0009] Figure 4 isFigure 2 Enlarged view of part B of the example.

[0010] Figure 5 It is a view of an example for explaining the phenomenon that the vibration of the printing medium affects the toner image.

[0011] Figure 6 and Figure 7 They are photos showing examples of the effects presented on the toner image.

[0012] Figure 8A It is a view of an example for explaining the movement guiding structure.

[0013] Figure 8B It is for explaining that the thick printing medium passes through Figure 8A A view of an example of the state of the movement guiding structure.

[0014] Figure 9 It is a view of an example for explaining the state of the thick printing medium passing through the guiding structure.

[0015] Figure 10 It is a photo showing an example of the recorded image formed on the thick printing medium.

[0016] Figure 11A It is a view for explaining the operation of the movement guiding structure in the image forming apparatus according to the example.

[0017] Figure 11B It is Figure 11A An enlarged view of a part of the example.

[0018] Figure 12A It is a view for explaining the operation of the movement guiding structure when the ordinary printing medium passes through the image forming apparatus according to the example.

[0019] Figure 12B It is Figure 12A An enlarged view of a part of the example.

[0020] Figure 13A It is a view for explaining the operation of the movement guiding structure when the thick printing medium passes through the image forming apparatus according to the example.

[0021] Figure 13B It is Figure 13A An enlarged view of a part of the example.

[0022] Figure 14 It is a partial perspective view for explaining the structure in which the movement guiding structure in the image forming apparatus moves synchronously with the movement of the transfer roller according to the example.

[0023] Figure 15 It is for explaining Figure 14Examples of views of the operation of a transfer roller, a link, and a movement guiding structure in an image forming apparatus.

[0024] Figure 16 is an example of a view for explaining the operation of a transfer roller, a link, and a movement guiding structure when a normal print medium is introduced Figure 15 into the transfer nip of an image forming apparatus.

[0025] Figure 17 is an example of a view for explaining the operation of a transfer roller, a link, and a movement guiding structure when a thick print medium is introduced Figure 15 into the transfer nip of an image forming apparatus.

[0026] Figure 18A and Figure 18B are views for describing a movement guiding structure according to another example.

[0027] Figure 19 is a view for explaining another transfer method according to an example.

[0028] Figure 20 is a perspective view of an image forming apparatus for explaining another example.

[0029] Figure 21 is a side view of an example of an image forming apparatus viewed from one side Figure 20 and

[0030] Figure 22 is a cross-sectional view of an example of an image forming apparatus taken along line C-C Figure 20 of DETAILED DESCRIPTION

[0031] Hereinafter, examples of a collator will be described with reference to the drawings. The same reference numerals always denote the same elements. In the drawings, the dimensions of the constituent elements may be enlarged for clarity.

[0032] Figure 1 is a schematic configuration diagram of an example of an image forming apparatus 1 according to an example.

[0033] Referring to Figure 1 , the image forming apparatus 1 shows a paper feeder 10 and a paper discharge tray 20. Print media are loaded on the paper feeder 10, and print media on which printing has been completed are loaded on the paper discharge tray 20. A print path 2 connects the paper feeder 10 to the paper discharge tray 20. An image forming unit 30 is arranged in the print path 2.

[0034] The print media P loaded on the paper feeder 10 are sequentially drawn out from the paper feeder 10 and transported along the print path 2. In this example, the paper feeder 10 is in the form of a cassette feeder, but the example of the paper feeder 10 is not limited thereto.

[0035] The image forming unit 30 prints an image on the print medium P that is conveyed along the print path 2 by an electrophotographic method. The image forming unit 30 may include a developing unit 40, an exposure unit 50, a transfer unit 100, and a fixing unit 60.

[0036] The image forming unit 30 of the present example can selectively print monochromatic images and color images on the print medium P.

[0037] For color printing, the developing unit 40 may include four developing units 40 for developing images of, for example, cyan (C), magenta (M), yellow (Y), and black (K). Each of the four developing units 40 may include a developer, such as a toner having cyan, magenta, yellow, or black. The cyan, magenta, yellow, and black toners are respectively accommodated in four toner supply containers (not shown), and the cyan, magenta, yellow, and black toners can be supplied from the four toner supply containers to the four developing units 40. In addition to the above colors, the image forming apparatus 1 may further include a developer for accommodating and developing toners of various colors (such as light magenta and white). When the accommodated toner is exhausted, the toner supply container can be replaced. The developing unit 40 may be detachably attached to the image forming apparatus 1 through a door (not shown).

[0038] Hereinafter, the image forming unit 30 having four developing units 40 will be described, and unless otherwise specified, the reference numerals with C, M, Y, and K respectively denote components for developing images of colors C, M, Y, and K.

[0039] The developing unit 40 supplies the toner accommodated therein to the electrostatic latent image formed on the photosensitive drum 41.

[0040] The photosensitive drum 41 is an example of a photoconductor on which an electrostatic latent image is formed, and may include a conductive metal tube and a photosensitive layer formed on the periphery of the conductive metal tube. The charging roller 43 charges the surface of the photosensitive drum 41 with a uniform electric potential.

[0041] The exposure unit 50 irradiates light modulated corresponding to the image information onto the photosensitive drum 41 to form an electrostatic latent image on the photosensitive drum 41. A laser scanning unit (LSU) using a laser diode as a light source, an LED exposure unit using a light emitting diode (LED) as a light source, etc. may be used as the exposure unit 50.

[0042] The developing roller 42 is used to develop an electrostatic latent image into a visible toner image by supplying a developer (such as toner) accommodated in the developing unit 40 to the photosensitive drum 41. A developing bias voltage can be applied to the developing roller 42. When a single-component developing method is adopted, the toner can be accommodated in the developing unit 40. When a two-component developing method is adopted, the toner and the carrier can be accommodated in the developing unit 40. Although not shown in the drawings, the developing unit 40 may further include a supply roller for supplying the developer accommodated in the developing unit 40 to the developing roller 42, an adjusting member attached to the surface of the developing roller 42 to adjust the amount of the developer supplied to the developing area where the photosensitive drum 41 and the developing roller 42 face each other, and a stirring member for the developer accommodated in the developing unit 40.

[0043] The transfer unit 100 may include an intermediate transfer belt 110, an intermediate transfer roller 102, and a transfer roller 120. The toner images developed on the photosensitive drums 41 in each of the developing units 40C, 40M, 40Y, and 40K are intermittently transferred to the intermediate transfer belt 110. The intermediate transfer belt 110 is supported by support rollers 103 and 104 and circulates.

[0044] The toner image is formed on the surface of the intermediate transfer belt 110. The surface of the intermediate transfer belt 110 on which the toner image is formed can move toward the transfer roller 120. The intermediate transfer belt 110 serves as an image carrier member for carrying the toner image.

[0045] Four intermediate transfer rollers 102 are arranged at positions facing the photosensitive drums 41 in each of the developing units 40C, 40M, 40Y, and 40K, with the intermediate transfer belt 110 between the intermediate transfer rollers 102 and the photosensitive drums 41. An intermediate transfer bias voltage for intermediate-transferring the toner image developed on the photosensitive drum 41 to the intermediate transfer belt 110 is applied to the four intermediate transfer rollers 102. A corona transfer unit or a pin scorotron transfer unit can be adopted to replace the intermediate transfer rollers 102. The transfer roller 120 is positioned facing the intermediate transfer belt 110. A transfer bias voltage for transferring the toner image intermediate-transferred to the intermediate transfer belt 110 to the print medium P is applied to the transfer roller 120.

[0046] When the transfer bias voltage is applied to the transfer roller 120, the toner image superimposed on the intermediate transfer belt 110 is transferred to the print medium P.

[0047] The fixing unit 60 applies heat and pressure to the print medium P onto which the toner image has been transferred, thereby fixing the toner image to the print medium P. The fixing unit 60 can be implemented in various forms. For example, the fixing unit 60 can include a heating member and a pressing member. The heating member and the pressing member are elastically pressed against each other to form a fixing nip. The heating member can be implemented in the form of, for example, a heating roller or a fixing belt. The heating member is heated by a heat source (such as a halogen lamp). The heating member contacts the image surface of the print medium P. The image surface is the surface onto which the toner image has been transferred. When the print medium P onto which the toner image has been transferred passes through the fixing nip, the toner image is fixed to the print medium P by heat and pressure. Therefore, in the image forming unit 30, a recorded image can be formed on the print medium P.

[0048] The pickup roller 12 sequentially extracts the print medium P from the feeder 11. The conveyance roller 13 conveys the extracted print medium P along the conveyance path. The conveyance roller 13 can include a pair of rollers that convey the print medium P when they are in contact with each other and rotating. The conveyance roller 13 aligns the leading edge of the print medium P according to the timing at which the leading edge of the toner image transferred to the intermediate transfer belt 110 reaches the transfer nip formed by the transfer roller 120 and the intermediate transfer belt 110, and conveys the print medium P to the transfer nip. The conveyance roller 13 is referred to as a registration roller. "Aligning the leading edge of the print medium P" means correcting the skew of the print medium P.

[0049] Figure 2 is an example of a view for conceptually explaining the operation of the transfer unit 100 of the image forming apparatus 1 according to the example. Figure 3 and Figure 4 are respectively Figure 2 example enlarged views of part A and part B of

[0050] See Figure 2 , a guiding structure for guiding the print medium P can be arranged between the transfer nip N and the conveyance roller 13 such that the print medium P is conveyed to the transfer nip N.

[0051] The guiding structure can be plural. That is, there can be more than one guiding structure, or the guiding structure can have more than one member. The guiding structure can include a movement guiding structure 130 and a guiding structure 150. The movement guiding structure 130 is arranged to face the first surface of the print medium P on which the toner image is formed, and the guiding structure 150 is arranged to face the second surface of the print medium P opposite to the first surface. The gap between the movement guiding structure 130 and the guiding structure 150 gradually decreases along the conveyance path of the print medium P. A guiding structure 160 can be additionally arranged between the movement guiding structure 130 and the conveyance roller 13.

[0052] The movement guiding structure 130 guides the print medium P conveyed through the conveying roller 13 to change its direction to face the transfer nip N. The guiding structure 150 can guide the print medium P to prevent the print medium P with a changed direction from colliding with the transfer roller 120 outside the transfer nip N.

[0053] Therefore, even if a curved path is included in the transmission path between the conveying roller 13 and the transfer nip N, the print medium P can reach the transfer nip N without hitting other structures through a plurality of guiding structures.

[0054] The movement guiding structure 130 has a certain distance from adjacent components, and a predetermined step (e.g., a height difference) can be formed between the movement guiding structure 130 and the adjacent components. For example, the movement guiding structure 130 is arranged to have a predetermined distance from the intermediate transfer belt 110 to prevent contact with the surface of the intermediate transfer belt 110. Therefore, a step can be formed between the movement guiding structure 130 and the intermediate transfer belt 110.

[0055] In addition, the movement guiding structure 130 is arranged at a predetermined distance from the guiding structure 160, and a predetermined step can be formed between the movement guiding structure 130 and the guiding structure 160. The predetermined step can prevent the print medium from being stuck in the movement guiding structure 130 during the process of the print medium moving from another guiding structure 160 to the movement guiding structure 130.

[0056] However, when these gaps or steps are larger than a predetermined size, image defects may be introduced during the process of transferring the toner image to the print medium P.

[0057] For example, as Figure 3 shown, during the process of the print medium P1 passing through the movement guiding structure 130 to the transfer nip N, the rear end of the print medium P1 passes between the movement guiding structure 130 and the intermediate transfer belt 110. The print medium P1 has elasticity. When the rear end of the print medium P1 is supported by the end 1301 of the movement guiding structure 130, due to the step between the movement guiding structure 130 and the intermediate transfer belt 110, the print medium P1 elastically bends, as Figure 3 shown by the dotted line. At the moment when the rear end of the print medium P1 passes the end 1301 of the movement guiding structure 130, as Figure 3 shown by the solid line, the print medium P1 returns to straight through the elastic recovery of the print medium P1, and the rear end of the print medium P1 contacts the intermediate transfer belt 110 through the elastic restoring force. At this time, vibration may occur at the rear end of the print medium P1.

[0058] In addition, as Figure 4As shown, while the rear end of the print medium P1 is being drawn out from the conveyance roller 13 and moving toward the transfer nip N, the rear end of the print medium P1 passes between the guide structure 160 and the movement guide structure 130. At the moment when the rear end of the print medium P1 passes the end of the guide structure 160, when the print medium P1 returns to being straight (as shown by the solid line in Figure 4 ), from the elastically bent state (as shown by the dashed line in Figure 4 ), the rear end of the print medium P1 contacts the movement guide structure 130. At this time, vibration may occur at the rear end of the print medium P1.

[0059] Thus, the vibration occurring at the rear end of the print medium P1 can be transmitted to a part of the print medium P1 adjacent to the transfer nip N, as shown in Figure 5 . The vibration may affect the toner image T on the intermediate transfer belt 110 or the transfer process in which the toner image T is transferred to the print medium P, resulting in image defects in the printed image. For example, as shown in Figure 6 , in the transferred toner image, some text lines may appear crushed, or as shown in Figure 7 , bands may appear in some areas of the print medium P1.

[0060] To prevent such unexpected image defects, the gap between the movement guide structure 130 and adjacent components is minimized. For example, a structure that reduces the gap between the end 1301 of the movement guide structure 130 and the intermediate transfer belt 110 can be considered.

[0061] However, when the movement guide structure 130 is fixed by reducing the gap between the end 1301 of the movement guide structure 130 and the intermediate transfer belt 110, unexpected image defects may occur during the process of forming an image on the thick print medium P2.

[0062] The print medium P used in the image forming apparatus 1 can have various thicknesses and weights. The weight of the print medium P is expressed as the basis weight. Hereinafter, the ordinary print medium is represented by P1, and the thick print medium is represented by P2.

[0063] For example, the ordinary print medium P1 can have a first thickness t1 and a predetermined basis weight. For example, the thickness of the ordinary print medium P1 can be about 0.3 mm or less. Again, for example, the thickness of the ordinary print medium P1 can be about 0.2 mm or less. For example, the ordinary print medium P1 can have a thickness of about 0.1 mm to about 0.2 mm, and the basis weight can be 60 g / m 2 to 120 g / m 2 .

[0064] For example, the thick printing medium P2 may have a second thickness t2 greater than the first thickness t1 and may have a basis weight greater than that of the ordinary printing medium P1. For example, the thick printing medium P2 has a thickness exceeding 0.3 mm, and the basis weight may be greater than 120 g / m 2 . For example, the thick printing medium P2 may have a thickness of approximately 0.4 mm and a basis weight of 325 g / m 2 .

[0065] Figure 8A and Figure 8B and Figure 9 are examples of views for explaining the state in which the thick printing medium P2 passes through the guiding structure.

[0066] See Figure 8A , the movement guiding structure 130 includes a guiding portion 1302 for guiding the printing media P1 and P2 to move along the surface and a supporting portion 1303 for supporting the guiding portion 1302 to be positioned at a predetermined position. The supporting portion 1303 is arranged at both ends of the guiding portion 1302. Thus, both ends of the movement guiding structure 130 are supported in the width direction of the printing medium P2.

[0067] During the process in which the printing media P1 and P2 are guided and move through the movement guiding structure 130, a predetermined force acts on the guiding portion 1302 through the printing media P1 and P2. In particular, since the middle portion 130-C of the movement guiding structure 130 is far from the supporting portion 1303, the middle portion 130-C is relatively easily bent by an external force.

[0068] When the thick printing medium P2 is guided and moves through the movement guiding structure 130, a predetermined force acts on the movement guiding structure 130 due to the thick printing medium P2. Since the basis weight of the thick printing medium P2 is greater than that of the ordinary printing medium P1, the force exerted on the movement guiding structure 130 by the thick printing medium P2 is greater than the force exerted on the movement guiding structure 130 by the ordinary printing medium P1.

[0069] When a predetermined force is applied to the relatively flexible movement guiding structure 130 due to the thick printing medium P2, the middle portion 130-C of the movement guiding structure 130 can bend from the state shown by the double-dashed line in Figure 8B to the state shown by the solid line in Figure 8B . Even if the degree of bending is small, when the gap between the movement guiding structure 130 and the intermediate transfer belt 110 is small, as shown in Figure 8B , the end portion 1301 of the movement guiding structure 130 may contact the intermediate transfer belt 110.

[0070] In addition, even if the middle portion 130-C of the movement guiding structure 130 does not bend, the end portion 1301 of the movement guiding structure 130 may also move fromFigure 9 The state indicated by the double-dashed line in Figure 9 is bent to the state indicated by the solid line in. For example, when the end portion 1301 of the movement guide structure 130 is thinner than other portions, the end portion 1301 of the movement guide structure 130 can be bent. Even if the degree of bending is small, when the gap between the movement guide structure 130 and the intermediate transfer belt 110 is small, as Figure 9 shown, the bent end portion 1301 of the movement guide structure 130 can also contact the surface of the intermediate transfer belt 110.

[0071] When the movement guide structure 130 contacts the surface of the intermediate transfer belt 110, serious image defects may occur. For example, when the end portion 1301 of the movement guide structure 130 contacts the surface of the intermediate transfer belt 110, the toner image T is scraped. Therefore, when the toner image T is transferred to the print medium P2, as Figure 10 shown, there may be a phenomenon that some areas in the recorded image formed on the print medium P2 are missing.

[0072] In view of this, when the print medium P2 is thick, in order to prevent the movement guide structure 130 from contacting the surface of the intermediate transfer belt 110 even if a part of the movement guide structure 130 is bent, the gap between the movement guide structure 130 and the intermediate transfer belt 110 is arranged to be a predetermined size or larger.

[0073] Thus, regarding the gap between the end portion 1301 of the movement guide structure 130 and the intermediate transfer belt 110, the conditions set when the print medium P is the ordinary print medium P1 and the conditions set when the print medium P is the thick print medium P2 conflict with each other.

[0074] Considering that opposite conditions are set according to the change in the thickness of the print medium P, the image forming apparatus 1 according to the example can have a structure that changes the gap between the end portion 1301 of the movement guide structure 130 and the intermediate transfer belt 110 according to the change in the thickness of the print medium P.

[0075] For example, the transfer roller 120 can move in a direction intersecting the drawing-out direction of the print medium P according to the thickness of the print medium P introduced into the transfer nip N, and the gap between the end portion 1301 of the movement guide structure 130 and the intermediate transfer belt 110 can be changed according to the movement of the position of the transfer roller 120.

[0076] According to an example, the image forming apparatus 1 includes an image bearing member (intermediate transfer belt 110), a transfer roller 120, and a movement guiding structure 130. In the image bearing member, a toner image is disposed on a movable surface. The transfer roller 120 faces the image bearing member 110 and moves in a direction intersecting with the introduction direction of the print medium P corresponding to the thickness of the print medium P. A transfer bias voltage is applied such that the toner image disposed on the image bearing member 110 is transferred to the print medium P. The movement guiding structure 130 is configured to guide the print medium P toward a transfer nip N formed between the image transfer member and the transfer roller 120. When the movement guiding structure 130 moves in synchronization with the position movement of the transfer roller 120, the gap between the end portion 1301 facing the image bearing member 110 and the image bearing member 110 changes.

[0077] Figures 11A to 13B are views for explaining the operations of the transfer roller 120 and the movement guiding structure 130 in the image forming apparatus 1 according to the example, where Figure 11A and Figure 11B show the operations when no print medium is introduced into the transfer nip N, Figure 12A and Figure 12B show the operations when the print medium P1 is introduced into the transfer nip N, and Figure 13A and Figure 3 B show the operations when the print medium P2 is introduced into the transfer nip N.

[0078] See Figure 11A and Figure 11B , when no print medium P is introduced into the transfer nip N, the transfer roller 120 contacts the intermediate transfer belt 110. The gap between the movement guiding structure 130 and the intermediate transfer belt 110 may have a reference gap G0. The reference gap G0 may be about 0.5 mm to about 1.3 mm.

[0079] When the thickness of the print medium P introduced into the transfer nip N is relatively thick, the gap between the end portion 1301 of the movement guiding structure 130 and the intermediate transfer belt 110 may increase.

[0080] See Figure 12A and Figure 12B , when the print medium P1 having a first thickness t1 is introduced into the transfer nip N, the transfer roller 120 and the intermediate transfer belt 110 are separated from each other by the first thickness t1. The rotation center of the transfer roller 120 moves a first distance D1 corresponding to the first thickness t1. The first distance D1 may be equal to or less than the first thickness t1. The first distance D1 may vary according to the elasticity of the outer surface of the transfer roller 120.

[0081] When the transfer roller 120 moves a first distance D1, the gap between the movement guiding structure 130 and the intermediate transfer belt 110 may have a first gap G1. The first gap G1 may be from about 0.7 mm to about 1.5 mm.

[0082] See Figure 13A and Figure 13B , when a print medium P2 having a second thickness t2 greater than the first thickness t1 is introduced into the transfer nip N, the transfer roller 120 and the intermediate transfer belt 110 are separated from each other by the second thickness t2. At this time, the rotation center C1 of the transfer roller 120 moves a second distance D2. The second distance D2 may be equal to or less than the second thickness t2. The second distance D2 may vary according to the elasticity of the outer surface of the transfer roller 120.

[0083] When the transfer roller 120 moves the second distance D2, the gap between the movement guiding structure 130 and the intermediate transfer belt 110 may have a second gap G2. The second gap G2 may be from about 1.3 mm to about 2.1 mm.

[0084] As described above, according to whether the print medium P is introduced into the transfer nip N or according to the thickness of the print medium P when the print medium P is introduced into the transfer nip N, the transfer roller 120 moves in a direction intersecting the introduction direction of the print medium P. The gap between the end 1301 of the movement guiding structure 130 and the intermediate transfer belt 110 can be adjusted by using the force that appears when the transfer roller 120 moves. In response to a change in the thickness of the print medium P, the gap between the movement guiding structure 130 and the intermediate transfer belt 110 changes so that the opposite conditions set for the movement guiding structure 130 can be satisfied according to the change in the thickness of the print medium P.

[0085] When various types of print media P are introduced into the transfer nip N, the position of the transfer roller 120 moves, and the gap between the movement guiding structure 130 and the intermediate transfer belt 110 can vary within a certain range. For example, when a 0.1 mm thick print medium P and a 0.4 mm thick print medium P are respectively introduced into the transfer nip N, the gap between the movement guiding structure 130 and the intermediate transfer belt 110 can vary from about 0.4 mm to about 2.1 mm.

[0086] Figure 14 is a partial perspective view of a structure for explaining the structure that moves in synchronization with the movement of the movement guiding structure 130 and the transfer roller 120 in the image forming apparatus according to the example. Figures 15 to 17 is for explaining Figure 14 the operation of the transfer roller 120, the link 140, and the movement guiding structure 130. Figure 18A and Figure 18B is a view for describing the movement guiding structures 130A and 130B according to another example;Figure 19 This is a view for explaining another transfer method.

[0087] Refer to Figure 14 and Figure 15 , the transfer roller 120 has a first rotating shaft 121 disposed at the rotation center C1. The transfer roller 120 is pressed by an elastic member 125 that provides an elastic force in a direction to keep in contact with the intermediate transfer belt 110, so as to form a transfer nip N with the intermediate transfer belt 110.

[0088] In the transfer roller 120 having such a structure, when the print medium P is introduced into the transfer nip N, the first rotating shaft 121 moves in a direction away from the intermediate transfer belt 110. On the other hand, when there is no print medium P in the transfer nip N, for example, after the print medium P is withdrawn from the transfer nip N, the first rotating shaft 121 moves in a direction approaching the intermediate transfer belt 110. The movement distance of the first rotating shaft 121 varies according to the change in the thickness of the print medium P. The thicker the print medium P, the greater the movement distance of the first rotating shaft 121.

[0089] The link 140 can be disposed at both ends of the transfer roller 120 in the width direction of the print medium P.

[0090] The link 140 transmits the position movement of the transfer roller 120 to the movement guiding structure 130. The link 140 rotates around a first rotation center C2 spaced apart from the rotation center C1 of the transfer roller 120.

[0091] The link 140 rotates along a first direction A1 synchronously with the position movement of the first rotating shaft 121 of the transfer roller 120. For example, the link 140 includes a first arm 142 extending from the first rotation center C2 and a second arm 143 extending from the first rotation center C2 in a direction different from that of the first arm 142 and being disposed to face the movement guiding structure 130. The first arm 142 and the second arm 143 are disposed in different directions from the first rotation center C2.

[0092] When the print medium P is introduced into the transfer nip N, the first arm 142 can be pressed by the first rotating shaft 121 of the transfer roller 120, while the second arm 143 can press the movement guiding structure 130.

[0093] The connecting rod 140 can be connected to a first elastic member 145 that provides an elastic force in a direction in which the first arm 142 approaches the first rotation axis 121 of the transfer roller 120. For example, the first elastic member 145 can be connected to the second arm 143. Thus, when the print medium P is introduced into the transfer nip N, the first rotation axis 121 of the transfer roller 120 pushes the first arm 142, causing the connecting rod 140 to rotate in a first direction A1. When the print medium P is withdrawn from the transfer nip N, the pressure applied by the first rotation axis 121 of the transfer roller 120 to the first arm 142 is released, causing the connecting rod 140 to rotate in a third direction A2 opposite to the first direction A1 through the first elastic member 145.

[0094] The movement guiding structure 130 is pressed by the second arm 143 so as to move toward the end portion 1301 of the intermediate transfer belt 110.

[0095] The movement guiding structure 130 can rotate about a second rotation center C3 spaced apart from the rotation center C1 of the transfer roller 120.

[0096] For example, the movement guiding structure 130 includes a third arm 132 and a fourth arm 133. The third arm 132 extends from the second rotation center C3 and is pressed by the second arm 143. The fourth arm 133 extends from the second rotation center C3 in a direction different from the direction of the third arm 132 and is arranged to face the intermediate transfer belt 110. The third arm 132 and the fourth arm 133 can be arranged in different directions from the second rotation center C3.

[0097] When the print medium P is introduced into the transfer nip N, the third arm 132 is pressed and moved by the second arm 143 due to the movement of the position of the first rotation axis 121 and the rotation of the connecting rod 140 in the first direction A1. Thus, the movement guiding structure 130 can rotate about the second rotation center C3 in a second direction B1, and the movement guiding structure 130 can move such that the end portion 1301 of the fourth arm 133 moves away from the surface of the intermediate transfer belt 110.

[0098] The movement guiding structure 130 can be connected to a second elastic member 135 that provides an elastic force in a direction in which the fourth arm 133 approaches the intermediate transfer belt 110. For example, the second elastic member 135 can be connected to the fourth arm 133.

[0099] When the print medium P is withdrawn from the transfer nip N, the pressure applied by the second arm 143 of the connecting rod 140 to the third arm 132 is released, causing the movement guiding structure 130 to rotate in a fourth direction B2 opposite to the second direction B1 through the second elastic member 135.

[0100] When the movement guiding structure 130 rotates in the fourth direction B2, the stopper 170 can be provided to limit the rotation range of the movement guiding structure 130 so that the end portion 1301 does not contact the intermediate transfer belt 110 and maintains the reference gap G0.

[0101] Reference will be made to Figures 15 to 17 describe the operation according to the above structure.

[0102] Refer to Figure 15 , when the printing medium P is not introduced into the transfer nip N, the intermediate transfer belt 110 and the transfer roller 120 are kept in contact by the elastic force provided by the elastic member 125 (refer to Figure 14 ). At this time, since the link 140 is pressed by the first elastic member 145 and rotates in the third direction A2, the first arm 142 remains in contact with the first rotation shaft 121 of the transfer roller 120. Since the movement guiding structure 130 is pressurized by the second elastic member 135 and rotates in the fourth direction B2, the third arm 132 remains in contact with the second arm 143 of the link 140.

[0103] Refer to Figure 16 , the printing medium P1 having the first thickness t1 passes through the movement guiding structure 130 and can be introduced into the transfer nip N. The first thickness t1 can be about 0.1 mm to about 0.2 mm.

[0104] When the printing medium P1 having the first thickness t1 is introduced, although there is the elastic force of the elastic member 125, the transfer roller 120 also moves backward in a direction intersecting the introduction direction of the printing medium P1. When the transfer roller 120 moves, the first rotation shaft 121 disposed at the rotation center C1 of the transfer roller 120 moves in the same direction. The movement distance of the first rotation shaft 121 is the first distance D1. The first distance D1 can be about 0.1 mm to about 0.2 mm. The first distance D1 can be equal to or less than the first thickness t1. For example, when the first thickness t1 is about 0.1 mm to about 0.2 mm, the first distance D1 can be about 0.05 mm to about 0.15 mm. For example, the first distance D1 can be about 50% to about 100% of the first thickness t1.

[0105] Due to the movement of the first rotation shaft 121 of the transfer roller 120, the first arm 142 in contact with the first rotation shaft 121 rotates around the first rotation center C2. Therefore, the second arm 143 connected to the first arm 142 rotates around the first rotation center C2.

[0106] Due to the rotational movement of the second arm 143, the third arm 132 in contact with the second arm 143 rotates around the second rotation center C3. Therefore, the fourth arm 133 connected to the third arm 132 rotates around the second rotation center C3.

[0107] Due to the rotational movement of the fourth arm 133, the gap between the intermediate transfer belt 110 and the end portion 1301 of the movement guiding structure 130 changes to a first gap G1 that is greater than the reference gap G0. For example, the first gap G1 can be 1.1 times to 1.9 times the reference gap G0.

[0108] See Figure 17 , a printing medium P2 having a second thickness t2 that is greater than the first thickness t1 passes through the movement guiding structure 130 and can be introduced into the transfer nip N. The second thickness t2 is greater than approximately 0.3 mm and can be 5 mm or less.

[0109] When the printing medium P1 having the second thickness t2 is introduced, the transfer roller 120 moves backward in a direction intersecting the introduction direction of the printing medium P1 despite the elastic force of the elastic member 125. When the transfer roller 120 moves, the first rotating shaft 121 disposed at the rotation center C1 of the transfer roller 120 moves in the same direction. The movement distance of the first rotating shaft 121 is a second distance D2, and the second distance D2 is greater than the first distance D1. The second distance D2 is greater than approximately 0.3 mm and can be 5 mm or less. The second distance D2 can be equal to or less than the second thickness t2. For example, when the second thickness t2 is approximately 0.4 mm, the first distance D1 can be approximately 0.2 mm to approximately 0.3 mm. For example, the second distance D2 can be approximately 50% to approximately 100% of the second thickness t2.

[0110] Due to the movement of the first rotating shaft 121 of the transfer roller 120, the first arm 142 in contact with the first rotating shaft 121 rotates around the first rotation center C2. Accordingly, the second arm 143 connected to the first arm 142 rotates around the first rotation center C2.

[0111] Due to the rotational movement of the second arm 143, the third arm 132 in contact with the second arm 143 rotates around the second rotation center C3. Accordingly, the fourth arm 133 connected to the third arm 132 rotates around the second rotation center C3.

[0112] Due to the rotational movement of the fourth arm 133, the gap between the intermediate transfer belt 110 and the end portion 1301 of the movement guiding structure 130 changes to a second gap G2 that is greater than the reference gap G0. For example, the second gap G2 can be approximately 1.4 times to approximately 3 times the reference gap G0.

[0113] Meanwhile, the difference between the reference gap G0 and the first gap G1 or the second gap G2 can be greater than the thicknesses of the introduced printing media P1 and P2. The reference gap G0 is the gap between the end 1301 of the movement guiding structure 130 and the intermediate transfer belt 110 as an image bearing member when the printing media P1 and P2 are not introduced into the transfer nip N. The first gap G1 or the second gap G2 is the gap between the end 1301 of the movement guiding structure 130 and the intermediate transfer belt 110 as an image bearing member when the printing media P1 and P2 are introduced into the transfer nip N. For example, the difference between the first gap G1 and the reference gap G0 can be about 1.5 times to about 8 times the first thickness t1. For example, the difference between the second gap G2 and the reference gap G0 can be about 1.5 times to about 8 times the second thickness t2.

[0114] Thus, when the movement distance of the end 1301 of the movement guiding structure 130 is greater than the thicknesses of the printing media P1 and P2, although the thickness change of the printing media P1 and P2 is small, the end 1301 of the movement guiding structure 130 can move to meet the opposite conditions set for the movement guiding structure 130.

[0115] Therefore, the link 140 and the movement guiding structure 130 can be designed in consideration of the thicknesses of the printing media P1 and P2 and the movement range set or provided for the movement guiding structure 130.

[0116] Referring again to Figure 15 , for example, the distance L1 from the first rotation center C2 to the point where the first arm 142 acts on the first rotation shaft 121 can be less than the distance L2 from the first rotation center C2 to the point where the second arm 143 contacts the third arm 132. The distance L1 can be about 30% or more and about 90% or less of the distance L2. For example, the distance L1 can be about 50% or more and about 80% or less of the distance L2.

[0117] The distance L3 from the second rotation center C3 to the point where the pressing force of the second arm 143 acts on the third arm 132 can be less than the distance L4 from the second rotation center C3 to the end 1301 of the fourth arm 133. The distance L3 can be about 5% or more and about 50% or less of the distance L4. For example, the distance L3 can be about 10% or more and about 25% or less of the distance L4.

[0118] By designing the distance L1 of the link 140 to be less than the distance L2 and the distance L3 of the movement guiding structure 130 to be less than the distance L4, the movement distance of the end 1301 of the movement guiding structure 130 can be greater than the movement distance of the transfer roller 120.

[0119] Accordingly, in the image forming apparatus 1 according to the example, by a mechanical structure synchronized with the movement of the transfer roller 120 (wherein a change in the thickness of the print medium P occurs without a complex sensor member for detecting the thickness of the individual print medium P), the distance between the end portion 1301 of the movement guiding structure 130 and the intermediate transfer belt 110 can be changed.

[0120] Meanwhile, referring again to Figure 11A and Figure 11B and Figure 15 the intermediate transfer belt 110 is disposed adjacent to the movement guiding structure 130 and the guiding structure 150. For example, the distance between the intermediate transfer belt 110 and the end portion of the guiding structure 150 may be from about 2 mm to about 10 mm. For example, the distance G4 between the intermediate transfer belt 110 and the end portion of the guiding structure 150 may be from about 2 mm to about 5 mm. Accordingly, the space for disposing the movement guiding structure 130 between the intermediate transfer belt 110 and the guiding structure 150 may be very narrow. As described above, the movement guiding structure 130 can be designed by considering disposing the movement guiding structure 130 in which the end portion 1301 can move in a narrow space.

[0121] For example, the movement guiding structure 130 may further include a rotating body 1342 that rotates about a second rotation center C3 and a guiding sheet 1341 that protrudes from the rotating body 1342 toward the intermediate transfer belt 110. A part of the guiding sheet 1341 and the rotating body 1342 constitute a third arm 132, and another part of the guiding sheet 1341 and the rotating body 1342 may constitute a fourth arm 133.

[0122] A part of the guiding sheet 1341 is supported by the rotating body 1342, and another part may protrude from the rotating body 1342 toward the intermediate transfer belt 110.

[0123] The protruding portion of the guiding sheet 1341 can be elastically deformed.

[0124] The thickness of the guiding sheet 1341 may be from about 0.05 mm to about 0.4 mm. By making the thickness of the guiding sheet 1341 thin, the guiding sheet 1341 can be positioned in a relatively narrow gap between the intermediate transfer belt 110 and the guiding structure 150 to guide the print medium P.

[0125] In the above example, the description focuses on the structure in which the movement guiding structure 130 is pressed and moved by the link 140. However, the connection between the movement guiding structure 130 and the transfer roller 120 is not limited thereto.

[0126] For example, as Figure 18AAs shown, the movement guiding structure 130A may have a structure that contacts the transfer roller 120 without the link 140. The movement guiding structure 130A may move in a certain direction by the movement of the transfer roller 120. The movement guiding structure 130A may rotate and move about a second rotation center C3 that is spaced apart from the rotation center C1 of the transfer roller 120. As another example, as Figure 18B shown, the movement guiding structure 130B may be slidably moved in a certain direction by the movement of the transfer roller 120 without rotating.

[0127] In Figures 1 to 18B the example disclosed, the structure in which the print medium P is transferred through the intermediate transfer belt 110 has been mainly described. However, the transfer method for image formation is not limited to this, and as Figure 19 shown, a transfer method may be used in which the toner image is directly transferred from the photosensitive drum 41 to the print medium P without the intermediate transfer belt 110. In this case, the toner image is disposed on the surface of the photosensitive drum 41 instead of the intermediate transfer belt 110, and the surface may rotate and move. In this case, the photosensitive drum 41 may be an image bearing member.

[0128] Meanwhile, the above example discloses an example of adjusting the movement of the movement guiding structures 130, 130A, and 130B by a mechanical structure (the position of the transfer roller 120 moves according to the change in the thickness of the print medium P) that is synchronized with the transfer roller 120. However, the present disclosure is not limited to this, and various structures may be applied.

[0129] Figure 20 is a perspective view for explaining an image forming apparatus 1A according to another example, Figure 21 is a side view of the image forming apparatus 1A viewed from one side, and Figure 20 is a cross-sectional view of the image forming apparatus 1A taken along the line C-C in Figure 22 In Figure 20 In order to facilitate description, a part of the image forming apparatus 1A is shown, and the remaining parts having a general configuration are omitted. Figure 20

[0130] Figures 20 to 22 Referring to , the image forming apparatus 1A according to the example may include a first rotating member 13A, a second rotating member 13B, and a thickness detector 180. The second rotating member 13B faces the first rotating member 13A, where the print medium P is introduced between the first rotating member 13A and the second rotating member 13B, and the second rotating member 13B moves in a direction intersecting the introduction direction of the print medium P according to the thickness of the introduced print medium P. The thickness detector 180 detects the thickness of the introduced print medium P based on the movement distance of the second rotating member 13B.

[0131] When the printing medium P is introduced between the first rotating member 13A and the second rotating member 13B, the rotating shaft 121A disposed at the rotation center C1 of the second rotating member 13B moves in a direction intersecting the introduction direction of the printing medium P. The rotating shaft 121A of the second rotating member 13B is pressed toward the first rotating member 13A by the elastic member 125A.

[0132] According to the thickness of the printing medium P, the second rotating member 13B has different movement distances. For example, when the printing medium P1 of the first thickness t1 (see Figure 16 ) is introduced between the first rotating member 13A and the second rotating member 13B, the rotating shaft 121A of the second rotating member 13B moves the first distance D1. When the printing medium P2 of the second thickness t2 (see Figure 17 ) is introduced between the first rotating member 13A and the second rotating member 13B, the rotating shaft 121A of the second rotating member 13B moves the second distance D2.

[0133] The thickness detector 180 can detect the thickness of the printing medium P based on the movement distance of the rotating shaft 121A of the second rotating member 13B. Here, the detection of the thickness includes determining whether the thickness is thick enough to exceed a certain standard and calculating the thickness value.

[0134] As an example, when the movement distance of the rotating shaft 121A of the second rotating member 13B is less than a certain distance, the thickness detector 180 can detect that the printing medium P is a general printing medium P1 having a relatively thin thickness. When the movement distance of the rotating shaft 121A of the second rotating member 13B is greater than a certain distance, the thickness detector 180 can detect that the printing medium P is a general printing medium P2 having a relatively thick thickness.

[0135] As another example, the thickness value of the printing medium P can be calculated in proportion to the movement distance of the rotating shaft 121A of the second rotating member 13B.

[0136] The link 140A can be disposed between the rotating shaft 121A of the second rotating member 13B and the thickness detector 180. The link 140A can rotate around the first rotation center C2 synchronously with the movement of the rotating shaft 121A of the second rotating member 13B.

[0137] As an example, the link 140A can include a first arm 142A and a second arm 143A extending from the first rotation center C2 in different directions. The first arm 142A is connected to the rotating shaft 121A of the second rotating member 13B. As an example, the first arm 142A can include an insertion hole 1420 into which the rotating shaft 121A of the second rotating member 13B is inserted. The second arm 143A is disposed adjacent to the thickness detector 180.

[0138] The first arm 142A rotates about the first rotation center C2 as the position of the rotation axis 121A of the second rotation member 13B moves. Accordingly, the second arm 143A connected to the first arm 142A rotates about the first rotation center C2.

[0139] The distance L6 from the first rotation center C2 to the point where the second arm 143A is inserted into the thickness detector 180 may be greater than the distance L5 from the first rotation center C2 to the point where the force on the rotation axis 121A acts on the first arm 142A. For example, the distance L6 from the first rotation center C2 to the point where the second arm 143A is inserted into the thickness detector 180 may be about 2.5 times to about 5.5 times the distance L5 from the first rotation center C2 to the point where the force on the rotation axis 121A acts on the first arm 142A.

[0140] Thereby, the movement distance D3 of the second arm 143A can increase according to the movement distance of the rotation axis 121A of the second rotation member 13B. For example, the movement distance of the region of the second arm 143A adjacent to the thickness detector 180 can increase by about 2.5 times to about 5.5 times according to the movement distance of the rotation axis 121A of the second rotation member 13B.

[0141] As an example, the thickness detector 180 can selectively detect whether the second arm 143A moves according to the thickness of the printing medium P.

[0142] For example, when the thickness of the printing medium P is less than or equal to a certain standard, the movement distance of the rotation axis 121A of the second rotation member 13B is relatively small. Accordingly, the movement distance D3 of the second arm 143A is also small. The certain standard can be, for example, about 0.3 mm or less. The certain standard can be, for example, about 0.2 mm or less.

[0143] When the movement distance D3 of the second arm 143A is small, the thickness detector 180 does not detect the movement of the second arm 143A. In this case, the thickness detector 180 can detect the introduced printing medium P as a normal printing medium P1.

[0144] Meanwhile, when the thickness of the printing medium P exceeds a certain standard, the movement distance of the rotation axis 121A of the second rotation member 13B is relatively large. Accordingly, the movement distance D3 of the second arm 143A is also large. When the movement distance D3 of the second arm 143A is equal to or greater than a certain size, the thickness detector 180 detects the movement of the second arm 143A. When detecting the movement of the second arm 143A, the thickness detector 180 can identify the introduced printing medium P as a thick printing medium P2.

[0145] The thickness detector 180 may be an optical sensor. However, the thickness detector 180 is not limited thereto, and any sensor for detecting whether the second arm 143A moves or detecting the amount of movement of the second arm 143A may be applied in various ways.

[0146] As another example, the thickness detector 180 may detect the movement distance of the second arm 143A.

[0147] For example, the thickness detector 180 may detect the movement distance of the second arm 143A and identify the thickness value of the print medium P corresponding to the detected movement distance. By presetting the thickness of the print medium P corresponding to the detected movement distance of the second arm 143A, the thickness of the print medium P can be calculated based on the detected movement distance of the second arm 143A. Since the thickness calculation uses a well-known method, its detailed description is omitted.

[0148] Therefore, in the image forming apparatus 1A according to the example, a method of detecting the thickness of the print medium P is used based on the movement of the second rotating member 13B, which is a structure in which mechanical movement occurs according to a change in the thickness of the print medium P. Thus, the error in detecting the thickness of the print medium P can be minimized.

[0149] When the thickness detector 180 directly detects the thickness of the print medium P, a detection error may occur depending on the printing conditions. For example, a method in which the thickness detector 180 directly irradiates an ultrasonic signal onto the print medium P and detects the thickness of the print medium P by the reflected ultrasonic wave can be considered. In this case, the ultrasonic signal detection may not be accurate due to various factors such as vibrations of the fast-transporting print medium P and changes in the surrounding environmental conditions.

[0150] On the other hand, by using a structure in which mechanical movement occurs when the thickness of the print medium P changes, the error or inaccuracy in signal detection that may occur in the process of detecting the thickness of the print medium P can be compensated to some extent.

[0151] It should be understood that the examples described herein should be considered merely descriptive and not for the purpose of limitation. The description of the features or aspects within each example should generally be considered applicable to other similar features or aspects in other examples. Although one or more examples have been described with reference to the accompanying drawings, those of ordinary skill in the art will understand that various forms and details can be changed therein without departing from the spirit and scope defined by the appended claims.

Claims

1. An image forming apparatus, comprising: An image bearing member including a movable surface for including a toner image; A transfer roller for forming a transfer nip between the transfer roller and the movable surface of the image bearing member, for performing a position movement in a direction intersecting the introduction direction of the print medium into the transfer nip corresponding to the thickness of the print medium, and for receiving a transfer bias voltage to transfer the toner image from the movable surface of the image bearing member to the print medium; And A movement guiding structure for guiding the print medium toward the transfer nip and for moving synchronously with the position movement of the transfer roller to change a gap between an end of the movement guiding structure facing the image bearing member and the image bearing member; Wherein when the thickness of the introduced print medium increases, the gap between the end of the movement guiding structure and the image bearing member increases; The image forming apparatus further includes a link for transmitting the position movement of the transfer roller to the movement guiding structure, the link for rotating about a first rotation center spaced apart from the rotation center of the transfer roller, and the link including a first arm and a second arm, the first arm extending from the first rotation center and being pressed by the transfer roller, and the second arm extending from the first rotation center in a direction different from the direction of the first arm and facing the movement guiding structure.

2. The image forming apparatus according to claim 1, wherein a difference between a gap between the end of the movement guiding structure and the image bearing member when the print medium is not introduced into the transfer nip and a gap between the end of the movement guiding structure and the image bearing member when the print medium is introduced into the transfer nip is greater than the thickness of the introduced print medium.

3. The image forming apparatus according to claim 1, wherein a distance from a point where the first arm is pressed by the transfer roller to the first rotation center is less than a distance from a point where the second arm contacts the movement guiding structure to the first rotation center.

4. The image forming apparatus according to claim 1, wherein the movement guiding structure is for rotating about a second rotation center spaced apart from the rotation center of the transfer roller, and The movement guiding structure includes a third arm and a fourth arm, the third arm extending from the second rotation center and being pressed by the second arm, and the fourth arm extending from the second rotation center in a direction different from the direction of the third arm and facing the movement guiding structure.

5. The image forming apparatus according to claim 4, wherein a distance from an end of the fourth arm facing the image bearing member to the second rotation center is greater than a distance from a point where the third arm is pressed by the second arm to the second rotation center.

6. The image forming apparatus according to claim 4, wherein the movement guiding structure includes: An elastic element for providing an elastic force to move the fourth arm toward the image bearing member; And A stopper for restricting the rotation range of the movement guiding structure.

7. The image forming apparatus according to claim 1, wherein the movement guiding structure includes: A rotating body for rotating about a second rotation center spaced apart from the rotation center of the transfer roller; And A guiding sheet having a thickness smaller than the thickness of the rotating body and protruding from the rotating body toward the image bearing member.

8. The image forming apparatus according to claim 7, wherein the thickness of the guiding sheet is from about 0.05 mm to about 0.4 mm.

9. The image forming apparatus according to claim 8, further comprising: A pair of transfer rollers upstream of the transfer path of the print medium for transferring the print medium between the image bearing member and the transfer roller; And A guiding structure between the transfer rollers and the transfer roller and facing a second surface of the print medium guided by the movement guiding structure opposite to the first surface.

10. The image forming apparatus according to claim 9, wherein the gap between the guiding structure and the movement guiding structure gradually narrows along the transfer path of the print medium.

11. The image forming apparatus according to claim 10, wherein the distance between the end of the guiding structure and the image bearing member is 2 mm to 10 mm.

Images