Image forming apparatus

Abstract

An image forming apparatus includes: an image forming section that forms an image on one face of a recording medium at an image forming position; a conveying section that conveys the recording medium while holding a leading end side of the recording medium, and passes the recording medium through the image forming position; a conveying body that supports the other face of the recording medium on which an image is formed by the image forming section while conveying the recording medium together with the conveying section; and a supporting section that supports the other face of the recording medium that is separated from the conveying body by conveying by the conveying section from the start of separation.

Description

Technical Field

[0001] This invention relates to an image forming apparatus. Background Technology

[0002] Patent document 1 discloses the following structure: a transfer material is transported by a conveying component consisting of a ring line, and the unfixed toner image transferred onto the transfer material is heated and melted by radiant heat.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2002-148973 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] As an image forming apparatus, a structure can be considered that includes: an image forming unit that forms an image on one surface of a recording medium at an image forming position; a transport unit that transports the recording medium while holding its front end side and passes it through the image forming position; and a transport body that supports the other side of the recording medium from which the image is formed by the image forming unit, and transports the recording medium together with the transport unit. In this structure, supporting the other side of the recording medium, which has separated from the transport body at its rear end after being transported by the transport unit, from the point of separation, can lead to recording medium wobbling.

[0008] At least one embodiment of the present invention supports the other side of the recording medium after it has separated from the transport body by the transport section from the point of separation, thus suppressing the shaking of the recording medium.

[0009] Methods for solving problems

[0010] The first embodiment is an image forming apparatus comprising: an image forming section that forms an image on one side of a recording medium at an image forming position; a transport section that transports the recording medium while holding the front end side of the recording medium and passes the recording medium through the image forming position; a transport body that supports the other side of the recording medium on which the image is formed by the image forming section while transporting the recording medium together with the transport section; and a support section that supports the other side of the recording medium that has separated from the transport body after being transported by the transport section, starting from before separation.

[0011] In the second embodiment, in the image forming apparatus of the first embodiment, the transport body transports the recording medium while clamping it between itself and the image forming unit, and the support unit begins to support the other side of the recording medium before the rear end of the recording medium has completely passed the clamping position between the transport body and the image forming unit.

[0012] In the third embodiment, in the image forming apparatus of the first or second embodiment, the support portion supports the other surface at a position further back than the holding position on the front end side of the recording medium held by the transport portion.

[0013] In the fourth embodiment, in any one of the first to third embodiments of the image forming apparatus, the support portion supports the other surface in a non-contact manner.

[0014] In the fifth embodiment, in the image forming apparatus of the fourth embodiment, the support portion is an air supply portion that blows air onto the other surface.

[0015] Invention Effects

[0016] According to the structure of the first method, compared with the structure that supports the other side of the recording medium after it has separated from the transport body by the transport section from the point of separation, the shaking of the recording medium is suppressed.

[0017] According to the structure of the second method, compared with the structure in which the support begins to support the other side of the recording medium after the rear end of the recording medium has completely passed through the clamping position of the transport body and the image forming unit, the shaking of the recording medium is suppressed.

[0018] According to the structure of the third method, compared with the structure in which the support part supports the other side at the same position as the holding position where the transport part holds the front end side of the recording medium, the shaking of the recording medium is suppressed.

[0019] According to the structure of the fourth method, compared with the structure in which the support part contacts the other side of the recording medium to support the recording medium, interference between the support part and the transport part is suppressed.

[0020] According to the structure of the fifth method, compared with the structure in which the support part supports the other side of the recording medium in a non-contact manner by magnetic or electrostatic force, the material used for the recording medium has a higher degree of freedom. Attached Figure Description

[0021] Figure 1 This is a schematic diagram showing the structure of the image forming apparatus of this embodiment.

[0022] Figure 2This is a schematic diagram showing the structure of the toner image forming section of this embodiment.

[0023] Figure 3 This is a schematic diagram showing the structure of the fixing device according to this embodiment.

[0024] Figure 4 This is a top view showing the structure of the fixing device according to this embodiment.

[0025] Figure 5 This is a schematic diagram showing an enlarged portion of the fixing unit of this embodiment.

[0026] Figure 6 This is a top view showing the fixing unit of this embodiment.

[0027] Figure 7 This is a perspective view showing a modified example of a chain gripper.

[0028] Figure 8 This is a side view showing a modified example of a blower.

[0029] Figure 9 This is a schematic diagram showing the structure of modified example 1.

[0030] Figure 10 This is a schematic diagram showing the structure of modified example 2. Detailed Implementation

[0031] An example of an embodiment of the present invention will be described below based on the accompanying drawings. Furthermore, in each figure, arrow H indicates the vertical direction, i.e., the up-down direction of the device; arrow W indicates the horizontal direction, i.e., the width direction of the device; and arrow D indicates the front-back direction of the device (the depth direction of the device).

[0032] (Image forming apparatus 10)

[0033] The structure of the image forming apparatus 10 of this embodiment will be described. Figure 1 This is a schematic diagram showing the structure of the image forming apparatus 10 of this embodiment.

[0034] Figure 1 The image forming apparatus 10 shown is an example of an image forming apparatus that forms an image on a recording medium. Specifically, the image forming apparatus 10 is an electrophotographic image forming apparatus that forms a toner image on paper P, which is an example of a recording medium. More specifically, as... Figure 1 As shown, the image forming apparatus 10 includes a receiving section 50, an exhaust section 52, an image forming section 12, an opposing roller 36, a conveying mechanism 60, a reversing mechanism 80, a fixing device 100, an air supply mechanism 170, and a cooling section 90.

[0035] (Containment Department 50)

[0036] Figure 1 The shown receiving section 50 functions to receive paper P. The image forming apparatus 10 includes multiple (e.g., two) receiving sections 50. It is configured to selectively feed paper P from these multiple receiving sections 50. The paper P, as an example of a recording medium, is a single sheet of paper (cut paper) of a predetermined size (dimension). Furthermore, the paper P has a surface PA (see reference 1) as an example of one side. Figure 5 ) and the back face PB as an example of another face (see Figure 5 The surface PA of paper P has an image area GR of the toner image (refer to). Figure 4 ), that is, the image region GR that forms the undefined image.

[0037] (Discharge section 52)

[0038] Figure 1 The discharge section 52 shown is the part that discharges the paper P on which the image is formed. Specifically, it is configured such that after the image is fixed by the fixing device 100, the paper P cooled by the cooling section 90 is discharged to the discharge section 52.

[0039] (Image forming section 12 and opposing roller 36)

[0040] Figure 1 The image forming unit 12 shown is an example of an image forming unit that forms an image on one surface of a recording medium. Specifically, the image forming unit 12 has the function of forming a toner image on the surface PA of paper P by electrophotography. More specifically, as Figure 1 As shown, the image forming unit 12 includes a toner image forming unit 20 for forming a toner image and a transfer device 30 for transferring the toner image formed by the toner image forming unit 20 onto paper P. The opposing roller 36 (or transfer cylinder, transfer body) is an example of a transport body. Furthermore, the structure of the opposing roller 36 will be described together with the structure of the transfer device 30.

[0041] Toner image forming section 20

[0042] The image forming apparatus 10 is equipped with multiple toner image forming units 20, which form toner images for each color. The image forming apparatus 10 includes toner image forming units 20 for a total of four colors: yellow (Y), magenta (M), cyan (C), and black (K). Figure 1 The (Y), (M), (C), and (K) shown represent the structural parts corresponding to the colors mentioned above.

[0043] The toner-forming section 20 is essentially the same in all aspects except for the toner used. Specifically, as... Figure 2 As shown, the toner image forming section 20 of each color has a lateral toner image forming section 20. Figure 2The image includes a photosensitive drum 21 (photoreceptor) rotating in the direction of arrow A and an electric charge device 22 that charges the photosensitive drum 21. Furthermore, the toner image forming unit 20 for each color includes: an exposure device 23 that exposes the photosensitive drum 21 charged by the electric charge device 22 to form an electrostatic latent image on the photosensitive drum 21; and a developing device 24 that develops the electrostatic latent image formed by the exposure device 23 on the photosensitive drum 21 to form a toner image.

[0044] Transfer device 30

[0045] Figure 1 The transfer apparatus 30 shown has the function of transferring the toner images of the photosensitive drums 21 of various colors onto an intermediate transfer body in a single overlapping manner, and then transferring the overlapping toner images onto the paper P in a second manner. Specifically, as Figure 1 As shown, the transfer device 30 includes a transfer belt 31 as an intermediate transfer body, a primary transfer roller 33, and a secondary transfer section 34.

[0046] The primary transfer roller 33 has a primary transfer position T (see [reference]) where the toner image formed on the photosensitive drum 21 is transferred between the photosensitive drum 21 and the primary transfer roller 33. Figure 2 The function of transferring the image from point 3 to transfer it onto transfer belt 31.

[0047] like Figure 1 As shown, the transfer belt 31 is looped and wound around a plurality of rollers 32 to determine its orientation. The transfer belt 31 is driven to rotate by at least one of the plurality of rollers 32 and wraps in the direction of arrow B, conveying the image after the first transfer to the secondary transfer position NT.

[0048] The opposing roller 36 is positioned below the transfer belt 31 in a manner opposite to the transfer belt 31. For example... Figure 1 As shown, the secondary transfer unit 34 is disposed inside the transfer belt 31 such that it is positioned between the secondary transfer unit 34 and the opposing roller 36. Specifically, the secondary transfer unit 34 is constructed using a corona tube. The secondary transfer position NT is located between the secondary transfer unit 34 and the opposing roller 36. At the secondary transfer position NT, the opposing roller 36 contacts the transfer belt 31. In this embodiment, the secondary transfer unit 34 and the opposing roller 36 constitute a transfer unit 35 that transfers the toner image transferred onto the transfer belt 31 onto the paper P. The secondary transfer position NT is an example of an image forming position.

[0049] In this embodiment, the paper P being conveyed, held at its front end by the chain gripper 66 (described later in the text) of the conveying mechanism 60, is positioned on the outer peripheral surface of the opposing roller 36. The chain gripper 66 and the opposing roller 36 convey the paper P, allowing it to pass through the secondary transfer position NT. That is, the opposing roller 36 conveys the paper P while supporting the back side PB of the paper P with its outer peripheral surface. The paper P, having passed through the secondary transfer position NT, is further conveyed by the chain gripper 66, and the rear end of the paper P separates from the opposing roller 36. In the transfer section 35, the toner image transferred to the transfer belt 31 is transferred to the paper P passing through the secondary transfer position NT by the electrostatic force generated by the discharge of the secondary transfer section 34. At the secondary transfer position NT, the opposing roller 36 and the transfer belt 31 convey the paper P while holding it. Therefore, the secondary transfer position NT can be described as the clamping position where the opposing roller 36 and the transfer belt 31 clamp the paper P.

[0050] (Conveying mechanism 60)

[0051] Figure 1 The conveying mechanism 60 shown is a mechanism for conveying paper P. Specifically, the conveying mechanism 60 has the function of conveying the paper P housed in the housing section 50 and passing it through the secondary transfer position NT. The conveying mechanism 60 also has the function of conveying the paper P from the secondary transfer position NT to the fixing unit 120 (the heating roller 130 and pressure roller 140 described later) in the fixing device 100. In other words, the conveying mechanism 60 has the function of conveying the paper P with the toner image transferred in the fixing device 100.

[0052] Specifically, such as Figure 1 As shown, the conveying mechanism 60 includes a feed roller 62, a plurality of conveying rollers 64, and a chain gripper 66. The feed roller 62 is the roller that feeds out the paper P housed in the receiving section 50. The plurality of conveying rollers 64 are the rollers that convey the paper P fed out by the feed roller 62 to the chain gripper 66.

[0053] like Figure 3 and Figure 4 As shown, the chain gripper 66 is a conveying unit that holds the front end (front side) of the paper P and conveys the paper P. Specifically, the chain gripper 66 includes a pair of chains 72 and a gripper 76 as a holding member (holding member).

[0054] like Figure 1 As shown, a pair of chains 72 are formed into a loop. These chains 72 are positioned in the front-to-back direction of the device. Figure 1 Arranged at intervals along the D direction (refer to) Figure 4Furthermore, a pair of chains 72 are wound around a pair of sprockets (not shown) respectively disposed on one end side and the other end side of the axial direction relative to the opposing roller 36 and the pressure roller 140 (described later), and a pair of sprockets 74 spaced apart in the front-rear direction of the device. By rotating any one of these sprockets, the chains 72 are configured to wrap around in the direction of arrow C (see reference). Figure 1 ).

[0055] like Figure 4 As shown, mounting members 75, on which clamps 76 are mounted, are mounted on a pair of chains 72 along the front-to-back direction of the device. Multiple mounting members 75 are fixed to the pair of chains 72 at predetermined intervals along the circumference (circumferential direction) of the chains 72. Furthermore, in each figure, to simplify the illustration of the chains 72, the structural portion of the chains 72 is represented as a block.

[0056] like Figure 4 As shown, multiple grippers 76 are mounted on the mounting member 75 at predetermined intervals along the front-rear direction of the device. The grippers 76 function to hold (hold) the front end of the paper P. By holding the front end of the paper P, the position of the paper P in the paper transport direction is easily determined, and the alignment (registration) of the paper P with the image in the transfer section 35 is easy. Specifically, as... Figure 3 and Figure 5 As shown, the gripper 76 has a jaw 76A and a jaw platform 76B. The gripper 76 is configured to hold the paper P by clamping the front end of the paper P between the jaw 76A and the jaw platform 76B. Specifically, the gripper 76 holds the image area GR (refer to) of the toner image transferred on the surface PA. Figure 4 The front end of the paper P is held externally. Furthermore, in this embodiment, a gripper 76, positioned downstream of the paper P in the transport direction, holds the front end of the paper P from the downstream side of the transport direction. Additionally, the gripper 76 presses the jaw 76A against the jaw table 76B via a spring, and opens and closes the jaw 76A relative to the jaw table 76B via a cam, etc. Furthermore, sometimes a cross mark, called a cross mark, is formed outside the image area GR; this mark is used for cutting to the finished size during printing and for registration in multicolor printing. Such an image can also be formed on... Figure 4 The position overlapping with the gripper 76 in the top view shown. Additionally, a portion of the gripper 76 may overlap with the image region GR, but should not overlap with the resulting image.

[0057] In the chain gripper 66, with the gripper 76 holding the front end of the paper P, the chain 72 wraps around in the direction of arrow C, thereby conveying the paper P. The chain gripper 66 conveys the paper P to the secondary transfer position NT with the surface PA of the paper P facing upwards, and then passes through the secondary transfer position NT. After the chain gripper 66 passes the heating unit 102 (described later), the paper P is conveyed to the fixing unit 120 (described later). Furthermore, since the chain gripper 66 holds the front end but not the rear end of the paper P, the rear end of the paper P is in a free state when only conveyed by the chain gripper 66.

[0058] As described above, the chain gripper 66 is a component that functions to pass the paper P through the heating unit 102 and to transport the paper P from the heating unit 102 to the fixing unit 120, and also serves as the fixing device 100. Furthermore, a portion of the transport path that transports the paper P in the transport mechanism 60 is... Figure 1 The text is represented by a single-dot dash. Additionally, in the following, the upstream direction of the conveying mechanism 60 conveying paper P will sometimes be referred to simply as "upstream," and the downstream direction will sometimes be referred to simply as "downstream."

[0059] (Reversal mechanism 80)

[0060] Figure 1 The reversing mechanism 80 shown is an example of a reversing mechanism that reverses the front and back of a recording medium on which an image has been fixed by a fixing device. Specifically, the reversing mechanism 80 is a mechanism that reverses the front and back of a piece of paper P on which a toner image has been fixed by the fixing device 100. More specifically, as... Figure 1 As shown, the reversing mechanism 80 has a plurality of (e.g., 2) conveying rollers 82, a reversing device 84, and a plurality of (e.g., 7) conveying rollers 86.

[0061] Multiple conveyor rollers 82 are rollers that convey the paper P from the fixing unit 100 to the reversing unit 84.

[0062] As an example, the reversing device 84 is a device that conveys the paper P by folding it back multiple times in a manner that changes the conveying direction of the paper P by, for example, by 90 degrees each time, thereby twisting the paper P like a Möbius strip and reversing the front and back of the paper P.

[0063] Multiple conveyor rollers 86 are rollers that transport paper P, which has been reversed in the reversing device 84, to the chain gripper 66. That is, multiple conveyor rollers 86 have the function of handing over the reversed paper P to the chain gripper 66.

[0064] In this way, the reverse mechanism 80 reverses the front and back of the paper P and hands the paper P over to the chain gripper 66. The chain gripper 66 transports the handed-over paper P as a paper P with a fixed toner image on the back side PB.

[0065] Furthermore, a portion of the conveying path of the paper P in the reversing mechanism 80 is in Figure 1 The text uses a single-dot dashed line to represent this. Alternatively, the reversing mechanism 80 can also be a mechanism that reverses the paper P by turning the paper P.

[0066] (Fixing device 100)

[0067] Figure 3 The fixing device 100 shown is an example of a fixing device that fixes an image formed by the image forming unit onto a recording medium. Specifically, the fixing device 100 is a device that fixes the toner image transferred by the transfer device 30 onto paper P.

[0068] like Figure 1 As shown, the fixing unit 100 is positioned downstream of the secondary transfer position NT in the paper transport direction of P. (As...) Figure 3 As shown, the fixing device 100 includes a heating unit 102, the aforementioned chain clamp 66, and a fixing unit 120 (fixing section).

[0069] Heating section 102

[0070] Figure 3 The heating unit 102 shown is an example of a heating unit that heats the surface of the recording medium in a non-contact manner. Specifically, the heating unit 102 has the function of heating the surface PA of the paper P conveyed by the chain gripper 66 in a non-contact manner.

[0071] The heating element 102 is positioned at the secondary transfer position NT (see reference) in the paper transport direction of the paper P. Figure 1 Downstream of the paper P, it is arranged opposite to the surface PA of the paper P conveyed by the chain gripper 66. Specifically, the heating unit 102 includes a reflector 104, a plurality of heaters 106 (heating sources) and a metal mesh 112.

[0072] Reflector 104

[0073] The reflector 104 has the function of reflecting infrared rays from the heater 106 toward the lower side of the device (the P side of the paper conveyed by the chain gripper 66). The reflector 104 is formed of a metal plate, such as an aluminum plate. The reflector 104 is formed into a box shape with an open lower side of the device.

[0074] Heater 106

[0075] Heater 106 is a cylindrical infrared heater with a length in the front-to-back direction of the device. Multiple heaters 106 (e.g., 40) are arranged inside the reflector 104 along the width direction of the device. Specifically, heater 106 is configured as a cylindrical quartz tube 108 containing carbon filaments 109 and housing the carbon filaments 109 internally. A black infrared emitting film is formed on the surface of the quartz tube 108. Thus, by forming a black infrared emitting film on the surface of the quartz tube 108, the heater 106 emits infrared rays more efficiently, for example, compared to the case where a white film is formed. Here, in this embodiment, black refers to a color whose chromaticity, measured in color difference ΔE, deviates from the achromatic point (x = 0.333, y = 0.333, Y = 0) by less than 100. Furthermore, in... Figure 3 In this embodiment, to illustrate the specific structure of the heater 106, it is enlarged and shown on the upper left side of the heating section 102. Furthermore, in this embodiment, the peak wavelength of the infrared radiation emitted by the infrared heater 106 is set to be 2 μm or more and 5 μm or less, which falls within the so-called far-infrared region. Moreover, the surface temperature of the heater 106 in the heating section 102 is a predetermined temperature of 300°C or more and 1175°C or less. Furthermore, in this embodiment, for a length of 1 m in the width direction of the reflector 104, heaters 106 are arranged at a density of 20 to 100 units in the width direction to efficiently emit far-infrared radiation, thereby achieving good heating distribution.

[0076] When a recording medium of A2 size or larger is transported with its transport direction as the long side and the toner on the recording medium is heated, if heating is performed using heaters 106 with fewer than 20 far-infrared rays per meter, the voltage applied to the carbon filament needs to be increased to improve the output of each heater 106. However, as the temperature of the black infrared radiation film rises, toner melting caused by heat conduction from the surrounding air heated by near-infrared light components becomes dominant compared to far-infrared radiation. As a result, uneven melting occurs near and between heaters 106. On the other hand, by having 20 or more filaments per meter, far-infrared radiation can be made dominant for the carbon filaments. Therefore, compared to the case with fewer than 20 filaments, far-infrared radiation, which has a low distance dependence on the radiation source for toner melting, can be effectively utilized, thus reducing uneven melting between heaters 106. Furthermore, if the number of electrodes exceeds 100, excessive far-infrared radiation will be emitted, making it difficult to control the temperature of the irradiated object to the point where the toner melts. Additionally, the fixing device located at the rear is also difficult to control due to the heat from the toner. Therefore, a number of electrodes of 100 or less is preferable. Particularly when transporting recording media of B2 size or larger with the transport direction of the recording medium as the long side, a number of electrodes of 30 to 50 is preferred.

[0077] Metal Mesh 112

[0078] The metal mesh 112 is fixed to the edge of the opening on the lower side of the reflector 104. Thus, the metal mesh 112 separates the interior of the reflector 104 from its exterior. Furthermore, the metal mesh 112 prevents the paper P conveyed by the chain gripper 66 from contacting the heater 106.

[0079] Chain gripper 66

[0080] Figure 3 The chain clamp 66 shown is an example of a transport unit that transports the recording medium while positioning the surface of the recording medium opposite the heating unit. The clamp 76 provided in the chain clamp 66 is an example of a holding unit that holds at least the front end side of the recording medium. Furthermore, the front end side of the recording medium refers to the portion of the recording medium that is downstream (front) from the center in the transport direction.

[0081] Specifically, as described above, with the gripper 76 holding the front end of the paper P, the chain 72 wraps around in the direction of arrow C, so that the chain gripper 66 transports the paper P while positioning the surface PA of the paper P against the heater 106 of the heating unit 102. That is, the chain gripper 66 has the function of allowing the paper P to pass through the heating area of ​​the heating unit 102. During the transport by the chain gripper 66, the rear end of the paper P is not held but is in a free state.

[0082] The chain gripper 66 also has the function of conveying the paper P from the heating unit 102 to the fixing unit 120. Thus, the chain gripper 66 functions as an example of the conveying unit of the fixing device 100 in the part that has the function of conveying the paper P through the heating area of ​​the heating unit 102 and from the heating unit 102 to the fixing unit 120.

[0083] Fixing unit 120

[0084] Figure 3 The fixing unit 120 shown is used to fix the image of paper P onto the fixing section of paper P. Specifically, the fixing unit 120 has the function of fixing the toner image onto paper P by heating and pressurizing the paper P through contact with it. In this embodiment, the heating section 102 that performs heating and pressurization is used for explanation, but heating is not necessarily required. If the purpose is to improve the surface properties of the toner melted in the heating section 102 of the previous process, such as adjusting the gloss, then a method based solely on pressurization of the pressing section can also be applied.

[0085] like Figure 3As shown, the fixing unit 120 is disposed downstream of the heating unit 102 in the paper transport direction of the paper P. Specifically, the fixing unit 120 includes a heating roller 130, a pressure roller 140, and a driven roller 150.

[0086] Heating roller 130

[0087] Figure 3 The heating roller 130 shown is an example of a heating component that is disposed downstream of the heating unit in the transport direction and heats the recording medium. Specifically, the heating roller 130 is disposed downstream of the heating unit 102 in the transport direction and has the function of heating the paper P by contacting it. The heating roller 130 is arranged axially in the front-back direction of the device in such a way that it contacts the surface PA of the paper P.

[0088] In addition, the heating roller 130 includes a cylindrical substrate 132, a rubber layer 134 formed on the outer periphery of the substrate 132, an anti-stick layer 136 formed on the outer periphery of the rubber layer 134, and a heater 138 (heating source) housed inside the substrate 132. The heater 138 is, for example, composed of one or more halogen lamps.

[0089] like Figure 6 As shown, the heating roller 130 is provided with a contact portion 139 that abuts against the contact portion 149 (described later) provided on the pressure roller 140. The contact portion 139 is an example of a contact portion provided on the heating roller. Specifically, the contact portion 139 is formed into a cylindrical shape having the same outer diameter as the heating roller 130. Furthermore, the contact portion 139 is provided at one end and the other end of the heating roller 130 in the axial direction so as to be coaxial with the heating roller 130 and rotate integrally with the heating roller 130.

[0090] Driven roller 150

[0091] Figure 3 The driven roller 150 shown is axially arranged in the front-to-back direction of the device to contact an area on the outer peripheral surface of the heating roller 130 other than the contact area of ​​the contact paper P. Furthermore, the driven roller 150 has a cylindrical substrate 152 and a heater 154 (heat source) housed inside the substrate 152. The driven roller 150 rotates driven by the heating roller 130, heating the heating roller 130. Since the heating roller 130 is heated by the driven roller 150 and the heating roller 130 itself has a heater 138, the surface temperature of the heating roller 130 becomes a predetermined temperature.

[0092] Pressure roller 140

[0093] Figure 3The pressure roller 140 shown is an example of a pressure-applying component that applies pressure to the recording medium between the pressure-applying component and the heating roller. A recess is formed on the outer peripheral surface of the pressure-applying component, into which the retaining portion enters. Specifically, the pressure roller 140 functions to apply pressure to the paper P by clamping it between itself and the heating roller 130. The pressure roller 140 is axially positioned below the heating roller 130 in the front-rear direction of the device.

[0094] The pressure roller 140 has a cylindrical substrate 142, a rubber layer 144 formed on the outer periphery of the substrate 142, and an anti-stick layer 146 formed on the outer periphery of the rubber layer 144.

[0095] The circumference of the pressure roller 140 is the same as the spacing between the grippers 76 and the chain 72. Furthermore, as... Figure 5 and Figure 6 As shown, a recess 148 extending in the front-rear direction of the device is formed on the outer peripheral surface of the pressure roller 140.

[0096] Furthermore, the clamp 76, which holds the front end of the paper P, is configured to enter the recess 148 when it passes between the pressure roller 140 and the heating roller 130.

[0097] In addition, such as Figure 6 As shown, the pressure roller 140 is provided with an abutting portion 149 that abuts against the abutting portion 139 of the heating roller 130. The abutting portion 149 is provided on the axially outer side of the recess of the pressure roller, and is an example of an abutting portion that abuts against the abutting portion 139 to maintain the axial distance between the heating roller 130 and the pressure roller 140.

[0098] The abutment portion 149 is formed as a cylinder having the same outer diameter as the pressure roller 140. The abutment portion 149 is provided on the axial outer side of the recess 148 of the pressure roller 140. Specifically, the abutment portion 149 is provided on one end and the other end of the pressure roller 140 in the axial direction so as to be coaxial with the pressure roller 140 and rotate integrally with the pressure roller 140.

[0099] By rotating the heating roller 130 and the pressure roller 140 with the contact portion 149 in contact with the contacted portion 139, even when the recess 148 is opposite the heating roller 130, the axial distance between the heating roller 130 and the pressure roller 140 is maintained. As a result, the pressure roller 140 is pressed down within a specific range by a load exerted by a force-applying member (not shown) toward the heating roller 130. The surface pressure in a conventional fuser is approximately 400 kPa.

[0100] In addition, in the fixing unit 120, the pressure roller 140 is driven to rotate by a drive unit (not shown), the heating roller 130 is driven to rotate by the pressure roller 140, and the driven roller 150 is driven to rotate by the heating roller 130.

[0101] Air supply unit 170

[0102] Figure 3 The air supply mechanism 170 shown is an example of a support portion and also an example of an air supply portion. This air supply mechanism 170 is a mechanism for blowing air onto the back surface PB of the paper P. Specifically, the air supply mechanism 170 has a blower 160 and a ventilation plate 180.

[0103] 160 blower

[0104] Figure 3 The blower 160 shown is a device that blows air toward the back side PB of the paper P. Viewed from the front-to-back direction, multiple blowers 160 are arranged inside the chain 72 (inner circumferential side) and below the heating unit 102. Figure 3 as well as Figure 4 As shown, multiple blowers 160 are arranged in a two-dimensional (matrix) configuration along the paper P conveying direction and the front-to-back direction of the device. Furthermore, in Figure 4 In order to simplify the illustration of the blower 160, some of the blades of the blower 160 have been omitted.

[0105] like Figure 3 As shown, the blower 160 is configured to face upwards and blow air upwards. That is, it is configured to blow air only onto the back side PB of the paper P, which is opposite to the heating unit 102, in the thickness direction of the paper P. In other words, the blower 160 is arranged opposite the back side PB of the paper P being conveyed by the chain gripper 66. In further terms, the chain gripper 66 is configured to convey the paper P while the back side PB of the paper P is opposite to the blower 160.

[0106] As an example, an axial flow fan that supplies air in the axial direction is used as the blower 160. Alternatively, a centrifugal fan that supplies air in the centrifugal direction, such as a multi-bladed fan (e.g., a Sirocco fan), can also be used as the blower 160.

[0107] In the blower 160, air is supplied to the back side PB of the paper P being conveyed by the chain gripper 66, causing the paper P to float. As a result, the back side PB of the paper P becomes non-contact. Specifically, at least the back side PB within the image area GR of the paper P becomes non-contact. More specifically, at least the back side PB within the image area GR of the paper P becomes non-contact relative to the ventilation plate 180. Therefore, the blower 160 has the function of maintaining this non-contact state, so that the paper P is conveyed by the chain gripper 66 without contacting the back side PB within the image area GR of the paper P. Furthermore, contact with the ventilation plate 180 is permitted for the back side PB outside the image area GR of the paper P. Additionally, it is necessary not to directly supply air blown from the air outlet of the blower 160 to the surface PA of the paper P. This is because the image forming apparatus 10 of this embodiment is an image forming apparatus that uses dry toner to form images; if air is supplied directly to the surface of the paper P from the air outlet, the unfixed toner image may be disturbed. In addition, by supplying air only to the back side PB, the cooling of the toner transferred to the surface PA can be suppressed.

[0108] Ventilation panel 180

[0109] Figure 3 The vent plate 180 shown is an example of a vent section having multiple vent holes through which air blown from the air supply section toward the back side of the recording medium passes. Specifically, the vent plate 180 is composed of a plate having multiple vent holes 182 through which air blown from the blower 160 toward the back side PB of the paper P passes.

[0110] Viewed from the front-to-back direction of the device, the vent plate 180 is positioned inside the chain 72 (inner circumferential side), below the heating unit 102, and above the blower 160, with the thickness direction of the device being vertical. That is, it is positioned to cover the blower 160 in the direction of airflow. In other words, the vent plate 180 can also be considered an example of a component positioned opposite the back side PB of the paper P conveyed by the chain gripper 66.

[0111] Each vent 182 extends through the vent plate 180 in the thickness direction. For example... Figure 4 As shown, multiple vents 182 are arranged in a two-dimensional (matrix) configuration along the paper P's conveying direction and the device's front-to-back direction. Additionally, in Figure 4 In order to simplify the illustration of the vent plate 180, a portion of the vent hole 182 has been omitted.

[0112] In the ventilation plate 180, air blown from the blower 160 passes through a plurality of ventilation holes 182 and comes into contact with the back side PB of the paper P conveyed by the chain gripper 66. In other words, the blower 160 is configured to deliver air to the back side PB of the paper P conveyed by the chain gripper 66 via the ventilation plate 180 having a plurality of ventilation holes 182.

[0113] The ventilation plate 180 is made of a metal plate. The ventilation plate 180 also functions as a reflector to reflect infrared rays from the heater 106 toward the upper side of the device (the paper P side conveyed by the chain gripper 66).

[0114] As described above, in the air supply mechanism 170, the blower 160 supplies air to the back side PB of the paper P conveyed by the chain gripper 66 via a vent plate 180 having a plurality of vent holes 182. Thus, the air supply mechanism 170 supports the paper P from the back side PB.

[0115] Configuration of air supply area in air supply unit 170

[0116] In the air supply unit 170, such as Figure 3 As shown, the upstream end 170X of the air supply area defined by the blower 160 and the vent plate 180 is positioned at the secondary transfer position NT and... Figure 3 The holding position 66X is shown. More specifically, the upstream end 170X is configured on the downstream side relative to the secondary transfer position NT, and on the upstream side relative to the holding position 66X.

[0117] Specifically, the upstream end 170X of the air supply area of ​​the air supply mechanism 170 is configured at... Figure 3 The shown separation position 36X is between the holding position 66X. Specifically, the upstream end 170X is configured on the downstream side relative to the separation position 36X and on the upstream side relative to the holding position 66X.

[0118] The separation position 36X is the position where the rear end of the paper P conveyed by the chain gripper 66 separates from the opposing roller 36. The separation position 36X can also be described as the downstream end of the area where the paper P contacts the outer peripheral surface of the opposing roller 36. In this embodiment, the separation position 36X is located downstream of the secondary transfer position NT. Depending on the situation, the rear end of the paper P separates at the downstream end 36Z of the opposing roller 36 (a position rotated 270 degrees to the right from the upper end of the opposing roller 36). That is, sometimes the separation position 36X is located at the downstream end 36Z of the opposing roller 36.

[0119] When the rear end of the paper P conveyed by the chain gripper 66 is in the separation position 36X, the holding position 66X is the position where the chain gripper 66 holds the paper P. Here, the paper P is the smallest size paper P used in the image forming apparatus 10. In addition, the holding position 66X can be any holding position defined by at least the largest size paper P used in the image forming apparatus 10.

[0120] Furthermore, in the air supply mechanism 170, air supply begins to support the back side PB before the rear end of the paper P passes the separation position 36X. That is, the air supply mechanism 170 begins to support the back side PB by air supply before the rear end of the paper P separates from the opposing roller 36. Specifically, the air supply mechanism 170 begins to support the back side PB by air supply before the rear end of the paper P has completely passed the secondary transfer position NT. In other words, the air supply mechanism 170 begins to support the back side PB by air supply while the paper P is passing through the secondary transfer position NT.

[0121] Furthermore, the air supply mechanism 170 supplies air to the back side PB of the paper P, which has passed the secondary transfer position NT, during the period until the rear end of the paper P reaches the downstream side of the air supply area, thus supporting the back side PB of the paper P. As described above, in the air supply mechanism 170, the back side PB of the paper P, which has been separated from the opposing roller 36 by the conveying of the chain gripper 66, is supported before separation. Since the airflow tends to become unstable when air supply begins, it is preferable to start air supply when the opposing roller 36 contacts the back side PB of the paper P (before separation).

[0122] Furthermore, as described above, the upstream end 170X of the air supply area of ​​the air supply mechanism 170 is arranged in... Figure 3 The separation position 36X and the holding position 66X are shown. Therefore, when air is supplied to the back side PB of the paper P at a position further back than the holding position 66X, the back side of the paper P is separated from the opposing roller 36. That is, when the air supply mechanism 170 supports the back side PB at a position further back than the holding position 66X, the back side of the paper P is separated from the opposing roller 36.

[0123] Furthermore, in the air supply mechanism 170, the air supply area set by the blower 160 and the ventilation plate 180 is configured such that it is longer upstream in the transport direction of the paper P than the heating area set by the aforementioned heating unit 102. That is, the paper P, after passing through the transfer unit 35, is ventilated on its back side PB by the blower 160 before entering the heating unit 102. As a result, the paper P is transported to the heating unit 102 in a stable posture. More preferably, the air supply area is set downstream in the transport direction of the paper P, starting from a position immediately following the transfer unit 35 and not overlapping with the transfer belt 31 in the direction of gravity.

[0124] Furthermore, in the air supply mechanism 170, the air supply area defined by the blower 160 and the vent plate 180 is set such that it is longer downstream of the paper P in the transport direction than the heating area defined by the aforementioned heating unit 102. That is, in the air supply mechanism 170, after passing through the heating area of ​​the heating unit 102, air is also supplied to the back surface PB of the paper P. As a result, the paper P is transported to the fixing unit 120 in a stable posture.

[0125] (Cooling section 90)

[0126] like Figure 1 As shown, the cooling unit 90 is disposed downstream of the fixing unit 120 in the paper transport direction of the paper P. Furthermore, the cooling unit 90 includes a plurality (e.g., two) of cooling rollers 92 arranged in the width direction of the device.

[0127] The cooling roller 92 is composed of a cylindrical roller formed of metal or the like. The cooling roller 92 is configured such that air flows inside it, thereby cooling the paper P by air cooling (heat exchange with the air).

[0128] (Supplement to image forming apparatus 10)

[0129] As an example, the length of the paper P used in the image forming apparatus 10 in the transport direction is 570 mm or more and 680 mm or less. Also, as an example, the distance between the plurality of grippers 76 arranged circumferentially along the chain 72 in the transport direction is 840 mm. Furthermore, as an example, the distance between the paper P held at each of the plurality of grippers 76 in the transport direction in the transport direction is 160 mm or more and 270 mm or less.

[0130] As an example, the distance L1 from the upstream end 170Z of the air supply mechanism 170 to the downstream end 36Z of the opposing roller 36 is 230mm or more and 260mm or less. As an example, the diameter of the opposing roller 36 is 285mm. In addition, as an example, the distance L2 from the secondary transfer position NT to the downstream end 36Z of the opposing roller 36 is 140mm.

[0131] The distance L3 from the upstream end of the heating section 102 (the upstream end of the heating area) to the downstream end 36Z of the opposing roller 36 can be greater than the maximum paper length of 680 mm. When the paper P burns in the heating section 102, if the paper P comes into contact with the opposing roller 36, the opposing roller 36 may burn, but in this structure, burning is avoided.

[0132] In addition, at least the upstream end of the upper surface of the air supply mechanism 170 (the upper surface of the vent plate 180 in this embodiment) or the upper surface of the air supply mechanism 170 (the upper surface of the vent plate 180 in this embodiment) and at least the upstream end of its air supply area are located at a position lower than the upper end of the opposing roller 36 in the direction of gravity.

[0133] In this embodiment, the upstream end 170Z of the air supply mechanism 170 and the upstream end 170X of the air supply area can be configured in... Figure 3 Between the separation position 36X and the holding position 66X shown, air supply can begin after the rear end of the paper P separates from the opposing roller 36 and before the paper P contacts the air supply mechanism 170 (blower 160 or ventilation plate 180). Furthermore, the contact between the paper P and the air supply mechanism 170 is caused by the paper P drooping. This structure can be implemented, for example, by starting air supply when the rear end of the paper P is detected by a sensor located downstream of the separation position 36X, or by starting air supply after a predetermined time has elapsed from the moment detected by a sensor located at a predetermined position. The predetermined time is measured by a timer or the like.

[0134] Alternatively, the structure could be as follows: after the paper P separates from the opposing roller 36, air supply begins before the rear end of the paper P falls on the upper surface of the air supply mechanism 170 in the direction of gravity and before it falls between the upstream end 170Z of the air supply mechanism 170 and the opposing roller 36. In this structure, for example, air supply can be initiated when the rear end of the paper P is detected by a sensor located downstream of the separation position 36X, or it can be initiated after a predetermined time has elapsed from the moment detected by a sensor located at a predetermined position. The predetermined time is measured by a timer or the like.

[0135] In this embodiment, the reflector 104 and the heat insulation cover are integrated. In addition, the upstream end 170Z of the air supply mechanism 170 and the upstream end 170X of the air supply area are located upstream of the heating part 102, and the air supply mechanism 170 and its air supply area exist upstream of the reflector 104 and the heat insulation cover.

[0136] Here, if the paper P comes into contact with heat-sensitive components such as the reflector 104 and the heat shield, the paper P may burn. Furthermore, contact with the paper P may also cause disruption of the toner image. In this embodiment, since the air supply mechanism 170 and its air supply area are located upstream of the reflector 104 and the heat shield, the paper P can be stably supported in a non-contact manner before passing through the reflector 104 and the heat shield.

[0137] Furthermore, the air supply mechanism 170 and its air supply area are located downstream of the reflector 104 and the heat shield. Therefore, after the paper P passes through the reflector 104 and the heat shield, the paper P is stably supported until it is conveyed to the fixing unit 120. Alternatively, the reflector 104 and the heat shield can also be constructed separately.

[0138] (The function of this implementation method)

[0139] from Figure 1 The paper P delivered from the receiving section 50 is conveyed by multiple conveyor rollers 64 and transferred to the chain gripper 66. The paper P, held at its leading end by the gripper 76, is conveyed by the chain gripper 66 to the secondary transfer position NT, where the toner image is transferred from the transfer belt 31 to the surface PA. Figure 3 As shown, the paper P with the toner image transferred is conveyed by the chain clamp 66 with the surface PA facing the heater 106 of the heating unit 102, and the toner image is heated.

[0140] The paper P, whose toner image has been heated by the heating unit 102, is further conveyed to the fixing unit 120 by the chain clamp 66 and is clamped between the heating roller 130 and the pressure roller 140, thereby being pressurized and heated. Thus, the toner image is fixed onto the paper P. When an image is formed only on the surface PA of the paper P, the paper P with the fixed toner image is... Figure 1 The cooling roller 92 of the cooling section 90 shown cools the product, and then it is discharged to the discharge section 52.

[0141] Here, in this embodiment, as described above, the back side PB of the paper P, which has been separated from the opposing roller 36 by the conveying of the chain gripper 66, is supported before separation by the air supply mechanism 170. That is, before the back side of the paper P is separated from the opposing roller 36, the air supply mechanism 170 begins to support the back side PB of the paper P by supplying air.

[0142] Incidentally, in the structure (hereinafter referred to as Structure A) where the back side PB of the paper P, after being separated from the opposing roller 36 by the conveyor via the chain gripper 66, is supported after separation due to the air supply mechanism 170, only the front end of the paper P is held by the chain gripper 66 during the period from the separation of the back end of the paper P from the opposing roller 36 until the back end of the paper P is supported by the air supply mechanism 170. Therefore, paper P may wobble. In particular, when paper P is thin, it is more prone to sagging and wobble compared to thicker paper. Furthermore, once paper P wobbles, it is difficult to control the wobble even after it is supported. Furthermore, especially when the unfixed image of the toner, which is an example of a powder, is located on the paper P between the secondary transfer position NT and the fixing unit 120, if the paper P shakes, the unfixed image may easily come into contact with other components within the image forming apparatus 10, or vibrations may occur due to the shaking. This could potentially cause disorder of the unfixed toner image, damage to the paper P, bending, etc. In addition, if the paper P shakes, it may easily come into contact with the heating unit 102, thereby not only causing disorder of the toner image on the surface of the paper P, but also potentially causing the paper P to burn.

[0143] In contrast, in this embodiment, since the back side PB of the paper P separated from the opposing roller 36 at the rear end is supported before separation, the wobbling of the paper P is suppressed compared to structure A. Thus, by suppressing the wobbling of the paper P, the disturbance of the toner image and the contact between the paper P and the heating unit 102 are suppressed.

[0144] Furthermore, in this embodiment, the air supply mechanism 170 begins to support the back side PB by supplying air before the rear end of the paper P has completely passed the secondary transfer position NT. That is, in this embodiment, the support of the back side PB begins from the state where the paper P is sandwiched between the opposing roller 36 and the transfer belt 31. Therefore, compared to the structure in which the air supply mechanism 170 begins to support the back side PB by supplying air after the rear end of the paper P has completely passed the secondary transfer position NT, the wobbling of the paper P is suppressed.

[0145] Furthermore, in this embodiment, the air supply mechanism 170 supports the back side PB at a position further back than the holding position where the chain gripper 66 holds the paper P. Therefore, compared to a structure where the air supply mechanism 170 supports the back side PB at the same position as the holding position where the chain gripper 66 holds the paper P, the wobbling of the paper P can be suppressed.

[0146] In addition, in this embodiment, the air supply mechanism 170 supports the back side PB of the paper P in a non-contact manner, so compared with the structure that supports the recording medium by contacting the back side PB of the paper P, the interference between the air supply mechanism 170 and the chain clamp 66 can be suppressed.

[0147] Furthermore, in this embodiment, since the back side PB of the paper P is supported by air supply, the material used as the recording medium has a higher degree of freedom compared to a structure that supports the back side PB of the paper P in a non-contact manner by magnetic or electrostatic force.

[0148] In addition, in this embodiment, such as Figure 3 As shown, in the heating section 102, the blower 160 blows air onto the back side PB of the paper P conveyed by the chain gripper 66, thereby maintaining the non-contact state so that the paper P is conveyed without contacting the back side PB in the image area GR of the paper P.

[0149] In the first structure (where the back side PB of the image area GR of the paper P is in contact with the structural part of the device while the surface PA is facing the heating unit 102 during paper P transport), the structural part (e.g., the vent plate 180) in contact with the paper P is heated by the heating unit 102 while the operation of the fixing device 100 continues, and the paper P is heated by the structural part to melt the toner.

[0150] As a result, the melting point of the toner changes during the initial operation of the fixing device 100 and as the operation of the fixing device 100 continues. Therefore, during the initial operation of the fixing device 100 and as the operation of the fixing device 100 continues, it is necessary to change the heating temperature of the heating unit 102 and the heating roller 130, making the control of the heating temperature complicated.

[0151] In contrast, in this embodiment, the blower 160 maintains this non-contact state, so that the paper P is conveyed without contacting the back side PB within the image area GR of the paper P. Therefore, compared with the first structure described above, the back side PB of the paper P is not heated, and the influence of heat (e.g., conductive heat) received from the back side PB of the paper P is reduced. In other words, the control of the heating temperature of the heating unit 102 and the heating roller 130 is prevented from becoming complicated, and the melting of the toner on the back side PB of the paper P due to heat during double-sided printing is prevented, as well as the disruption of the toner image caused by contact between the back side PB of the paper P and the blower 170 is prevented.

[0152] In particular, when images are formed on both sides of paper P, even when paper P with a fixed toner image on the back side PB is conveyed by the chain clamp 66 to the heating unit 102, the back side PB of paper P is not heated, thus suppressing the melting of the fixed toner image compared to the first structure. Furthermore, specifically for the purpose of suppressing the melting of the fixed toner image during double-sided image formation on paper P, the conveying unit and the air supply unit are controlled so that the back side PB of paper P, with a fixed toner image on the back side PB, remains in a non-contact state when passing through the heating unit 102. Even when the back side PB of paper P does not have a fixed toner image but only an unfixed toner image on the surface PA, the paper can be conveyed while the ventilation plate 180 and the like remain in contact with the back side PB.

[0153] Furthermore, in this embodiment, in the heating unit 102, the blower 160 blows air onto the back surface PB of the paper P conveyed by the chain gripper 66 via a vent plate 180 having multiple vent holes 182. Therefore, compared to the structure (second structure) where the air blown from the blower 160 directly contacts the back surface PB of the paper P without passing through the vent holes 182, uneven contact between the air and the back surface PB of the paper P can be suppressed. Consequently, compared to the aforementioned second structure, the posture of the paper P is less prone to change.

[0154] In this embodiment, such as Figure 5 As shown, when the gripper 76 holding the front end of the paper P passes between the pressure roller 140 and the heating roller 130, the gripper 76 enters the recess 148. Therefore, compared with the structure in which the paper P is pressed between the pressure roller 140 and the heating roller 130 without forming the recess 148, the gripper 76 is less likely to become an obstacle when the paper P is pressed.

[0155] In this embodiment, in Figure 6 When the abutting portion 149 is in contact with the abutted portion 139, even if the heating roller 130 and the pressure roller 140 rotate to form a recess 148 facing the heating roller 130, the interaxial distance between the heating roller 130 and the pressure roller 140 is maintained. Therefore, compared to a structure where pressure is applied to the paper P between the pressure roller 140 and the heating roller 130 without maintaining the interaxial distance, fluctuations in the pressure applied to the paper P are suppressed.

[0156] (A variation of the chain gripper 66)

[0157] In this embodiment, in the chain gripper 66, the gripper 76, positioned downstream of the paper P in the conveying direction, holds the front end of the paper P from the downstream side of the conveying direction, but is not limited to this. As an example of a holding part, such as... Figure 7As shown, a clamp 761, which is configured on both sides of the paper P, can also be used to hold the front end portion of the paper P from the side end of the paper P.

[0158] (Other variations)

[0159] In this embodiment, paper P is used as an example of a recording medium, but it is not limited to this. For example, a film may be used as a recording medium, and a sheet material other than paper P that is formed into a sheet (paper-like or film-like) may also be used as a recording medium.

[0160] Furthermore, in this embodiment, the image forming unit 12 has a structure having a transfer belt 31 as an intermediate transfer body, but it is not limited to this. As an example of an image forming unit, it could also be a direct transfer type image forming unit. Alternatively, as an example of an image forming unit, it could also be an inkjet type image forming unit that forms an image by spraying ink onto paper P.

[0161] In this embodiment, the conveying body is the opposing roller 36 of the transfer section 35, but it is not limited to this. The opposing roller 36 may also be a support roller or support block that supports the back side PB of the paper P conveyed from the transfer section 35. In this case, when the paper P is held by the transfer section 35, the support roller is preferably positioned at the position supporting the paper P. In addition, it is preferable that the surface of the paper P does not come into contact with other components during the period from leaving the transfer section 35 until the heating section 102, or during the period from leaving the transfer section 35 until the fixing unit 120.

[0162] Furthermore, in this embodiment, the separation position 36X is located downstream of the secondary transfer position NT, but it is not limited to this. For example, the separation position 36X may also be located downstream of the secondary transfer position NT. That is, it may be a structure in which the rear end of the paper P completely passes through the secondary transfer position NT, and the rear end of the paper P separates from the opposing roller 36. In addition, in the case where an inkjet image forming unit or the like is used as an example of an image forming unit, the structure is set as follows: there is no secondary transfer position NT (clamping position), the paper P is not clamped after being placed on the outer peripheral surface of the opposing roller 36, and the rear end separates from the opposing roller 36.

[0163] In this embodiment, the air supply mechanism 170 includes a blower 160 and a vent plate 180, but is not limited thereto. The air supply mechanism 170 may also have a structure that does not have a vent plate 180 but only has a blower 160.

[0164] In this embodiment, the air supply mechanism 170 begins to support the back side PB by supplying air before the rear end of the paper P has completely passed the secondary transfer position NT, but it is not limited to this. The air supply mechanism 170 may begin to support the back side PB by supplying air after the rear end of the paper P has completely passed the secondary transfer position NT, as long as it is before the rear end of the paper P separates from the opposing roller 36. Alternatively, air supply may begin before the paper P enters the secondary transfer position NT during image formation, or it may continue to supply air throughout image formation.

[0165] Furthermore, in this embodiment, the air supply mechanism 170 supports the back side PB at a position further back than the holding position where the chain gripper 66 holds the paper P, but it is not limited to this. For example, if the chain gripper 66 holds the paper P at the front end of the paper P in a manner close to the center in the transport direction, the air supply mechanism 170 may also be configured to support the back side PB at the same position as the holding position where the chain gripper 66 holds the paper P.

[0166] Furthermore, in this embodiment, the air supply mechanism 170 supports the back surface PB of the paper P in a non-contact manner, but it is not limited to this. For example, as an example of a support portion, it may also be a structure that supports the recording medium in contact with the back surface PB of the paper P.

[0167] Furthermore, in this embodiment, the back surface PB of the paper P is supported by air supply, but it is not limited to this. For example, as an example of a support, the back surface PB of the paper P can also be supported in a non-contact manner using magnetic or electrostatic forces.

[0168] In this embodiment, the blower 160 blows air toward the back surface PB of the paper P in the thickness direction, but is not limited to this. For example, the blower 160 may also blow air at an angle relative to the thickness direction of the paper P. For example, the blower 160 may be configured to be angled toward the upstream side of the paper P in the conveying direction (in... Figure 3 Air is supplied to the back of paper P (from the middle to the upper right) via PB.

[0169] And, as Figure 8 As shown, it can also be configured such that the blower 160 is positioned outside the width direction of the paper P, blowing air from both sides of the paper P onto the back surface PB of the paper P. In other words, any structure that supplies air to the back surface PB of the paper P to make the paper P float is acceptable.

[0170] Furthermore, in this embodiment, air is supplied only to the back surface PB of the paper P, but it is not limited to this. From the following perspective, it is permissible to supply air to the surface PA of the paper P.

[0171] Figure 9The example shown is a modified example 1, which supplies air to the surface PA from the viewpoint of stable feeding of paper P. In this modified example 1, except... Figure 3 In addition to the structure shown in this embodiment, a blower 190 is provided, positioned opposite to the surface PA side of the paper P, for supplying air to the surface PA. The relative airflow from the blower 190 and the blower 160 is adjusted to maintain the paper P in a position parallel to the transport direction. In this case, from the viewpoint of using dry toner, the airflow of the blower 190 is set to be smaller than that of the blower 160, and to a degree that the toner will not be dispersed by the air from the blower 190.

[0172] In addition, Figure 10 In Modification 2, to ventilate the air surrounding the heating unit 102, the blower 200 is positioned in a direction orthogonal to the airflow direction of the blower 160. That is, the air outlet of the blower 200 opens in the direction along the surface PA of the paper P, and is positioned so as not to face the surface PA of the paper P. Furthermore, the air blown from the blower 200 flows in the direction along the surface PA of the paper P, and the air from the blower 200 may be supplied to the surface PA of the paper P. In this case, it is also preferable, as in Modification 1, to set the airflow rate to a level that does not cause toner dispersion.

[0173] Furthermore, in this embodiment, the method of blowing air onto the back surface PB of the paper P in the thickness direction using the blower 160 is described. When there is no recording medium between the heating unit 102 and the blower 160, if the blower 160 is used, the heated air around the heating unit 102 may diffuse into the device. As a countermeasure to this problem, if the blower 160 blows air when the recording medium is facing the blower 160, the blown air is blocked by the recording medium. In other words, by reducing or stopping the airflow between the preceding and subsequent recording media, the amount of air supplied to the heating unit 102 from the blower 160 is reduced, thereby suppressing the diffusion of heated air into the device. This allows for both drive control of the blower 160 and individual drive control of multiple blowers 160.

[0174] This invention is not limited to the embodiments described above, and various modifications, alterations, and improvements can be made without departing from its spirit. For example, multiple variations shown above can be appropriately combined to form a complete system.

[0175] This application is based on Japanese Patent Application No. 2020-155743, filed on September 16, 2020, the contents of which are incorporated herein by reference.

[0176] Symbol Explanation

[0177] 10 Image forming apparatus

[0178] 12 Image Forming Unit

[0179] 36 opposing rollers (an example of a conveyor body)

[0180] 66 Chain gripper (an example of a conveyor unit)

[0181] 170 Air supply mechanism (an example of a support section, an example of an air supply section)

[0182] NT secondary transfer position (an example of image formation position)

[0183] Paper (an example of a recording medium)

[0184] PA surface (an example of one facet)

[0185] The back of PB (an example of another side)

Claims

1. An image forming apparatus comprising: An image forming unit that forms an image at an image forming position on one surface of a recording medium; A transport unit that transports the recording medium while holding the front end of the recording medium, and positions the recording medium through the image forming point; A transport body that supports one side of a recording medium on which an image is formed by the image forming unit, and transports the recording medium together with the transport unit; A heating element that heats the surface of the recording medium in a non-contact manner on the downstream side of the conveyor; and A support portion, which supports the other side of the recording medium that has been separated from the transport body by the transport portion from the beginning of separation, and an air supply portion that blows air onto the other side. The transport body transports the recording medium while it is sandwiched between itself and the image forming unit. The support portion begins to support the other side before the rear end of the recording medium has completely passed the clamping position between the transport body and the image forming unit. The support region of the support portion is configured to be longer upstream of the recording medium in the transport direction than the heating region of the heating portion, and is configured to be longer downstream of the recording medium in the transport direction than the heating region of the heating portion.

2. The image forming apparatus according to claim 1, wherein, The support portion supports the other surface at a position further back than the holding position on the front end side of the recording medium held by the transport portion.

Images