Image forming apparatus

Abstract

To collect UFPs without increasing the size of the device, while also properly discharging water vapor to the outside of the device. [Solution] The image forming apparatus 100 has an exhaust duct 114 that draws in air from inside the image forming apparatus 100 and exhausts it to the outside of the image forming apparatus 100. The exhaust duct 114 has a first intake section 104a located between the transfer nip section T2 and the fixing nip section T3 and equipped with an intake port 104c for drawing in air and a filter 102, and a second intake section 104b located between the fixing nip section T3 and the paper discharge roller 115 and equipped with an intake port 104d for drawing in air.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine having a plurality of functions thereof, which forms an image on a sheet.

Background Art

[0002] Generally, in an electrophotographic image forming apparatus, a toner image is formed on a sheet material using a toner that holds a release agent in an image forming unit. Further, the image forming apparatus fixes the toner image on the sheet material by heating and pressurizing the sheet material on which the toner image is formed in a fixing unit. At this time, in the fixing unit, water vapor held inside the sheet material evaporates when the sheet material is heated. Such water vapor may cause condensation when it adheres to a conveyance path or the like inside the apparatus, leading to quality problems such as image defects, and thus it is required to be appropriately discharged outside the apparatus.

[0003] In the fixing unit, when the release agent contained in the toner is heated, VOC (Volatile Organic Compounds) is released from the surface of the heated part at a high temperature, the toner, or the sheet material. Further, in the fixing unit, when the release agent contained in the toner is heated, UFP (Ultra Fine Particles) is released from the surface of the heated part at a high temperature, the toner, or the sheet material.

[0004] Here, UFP has a particle size of 100 nm or less. In recent years, in view of the influence of UFP on the human body, regulations on the emission amount of fine particles from image forming apparatuses have been progressing, and in particular, regulations such as the Blue Angel regulations, which are environmental regulations in Europe, are well known. Such environmental regulations are expected to become stricter in the future, and the installation of a mechanism for reducing UFP in image forming apparatuses is also underway.

[0005] In this context, Patent Document 1 discloses an image forming apparatus having a configuration that reduces UFP while discharging water vapor, by switching between a path for discharging water vapor to the outside of the machine and a path for collecting UFP using a shutter. The image forming apparatus of Patent Document 1 is provided with a filter for collecting UFP in the path for collecting UFP.

[0006] On the other hand, in recent years there has been a demand for small-sized and high-productivity image forming machines. To achieve high productivity, it is necessary to set the temperature control temperature of the fuser higher. Consequently, the generation of UFPs increases. In addition, with higher productivity, the frequency of paper passing through the fuser per unit time also increases, so the amount of water vapor generated tends to increase as well. Therefore, recent image forming machines need to efficiently achieve water vapor exhaust and UFP collection within a small space. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2015-219432 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, in Patent Document 1, the configuration involves switching between a path for discharging water vapor outside the device and a path for collecting UFPs using a shutter, which requires a lot of space to accommodate the shutter and the mechanism for switching with the shutter. Therefore, Patent Document 1 has the problem of making the device large.

[0009] The object of the present invention is to provide an image forming apparatus that can collect UFPs without increasing the size of the apparatus, and can also appropriately discharge water vapor to the outside of the apparatus. [Means for solving the problem]

[0010] The present invention relates to an image forming apparatus for forming an image on a sheet material, comprising: an image forming unit that forms a toner image using toner; a transfer unit that includes a transfer nip unit for transferring the toner image formed by the image forming unit to the sheet material; a fixing unit that includes a fixing nip unit for heating the sheet material on which the toner image has been transferred in the transfer nip unit to fix the toner image to the sheet material; a transport member for transporting the sheet material on which the toner image has been fixed in the fixing nip unit; and an exhaust duct equipped with a filter for drawing in air from inside the image forming apparatus and exhausting it to the outside of the image forming apparatus, wherein the exhaust duct comprises a first intake unit located between the transfer nip unit and the fixing nip unit and equipped with an intake port for drawing in air and the filter; and a second intake unit located between the fixing nip unit and the transport member and equipped with an intake port for drawing in air. [Effects of the Invention]

[0011] According to the present invention, UFPs can be collected without increasing the size of the device, and water vapor can be appropriately discharged to the outside of the device. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram of an image forming apparatus according to Embodiment 1 of the present invention. [Figure 2] This is a schematic diagram of a part of an image forming apparatus according to Embodiment 1 of the present invention. [Figure 3] This is a partial cross-sectional view of an image forming apparatus according to Embodiment 1 of the present invention. [Figure 4] This is a schematic diagram of a part of an image forming apparatus according to Embodiment 2 of the present invention. [Figure 5] This is a partial cross-sectional view of an image forming apparatus according to Embodiment 2 of the present invention. [Figure 6] This is a schematic diagram of a part of an image forming apparatus compared with an image forming apparatus according to Embodiment 2 of the present invention. [Figure 7]It is a diagram showing the relationship between the opening height and the intake air volume in the exhaust duct of the image forming apparatus according to Embodiment 2 of the present invention. [Figure 8] It is a partial schematic diagram of a modification of the image forming apparatus according to Embodiment 2 of the present invention. [Figure 9] It is a partial schematic diagram of the image forming apparatus according to Embodiment 3 of the present invention. [Figure 10] It is a partial schematic diagram of the image forming apparatus according to Embodiment 4 of the present invention. [Figure 11] It is a partial cross-sectional view of the image forming apparatus according to Embodiment 4 of the present invention. [Figure 12] It is a partial schematic diagram of a modification of the image forming apparatus according to Embodiment 4 of the present invention. [Figure 13] It is a partial cross-sectional view of a modification of the image forming apparatus according to Embodiment 4 of the present invention. [Figure 14] It is a partial schematic diagram of the image forming apparatus according to Embodiment 5 of the present invention.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the X direction is the left-right direction, the Y direction is the front-back direction, and the Z direction is the up-down direction.

[0014] (Embodiment 1) <Configuration of the Image Forming Apparatus> The configuration of the image forming apparatus 100 according to Embodiment 1 of the present invention will be described in detail while referring to FIG. 1.

[0015] The image forming apparatus 100 exemplifies a laser printer here. The image forming apparatus 100 includes an image forming unit PY, an image forming unit PM, an image forming unit PC, an image forming unit PK, a laser scanner unit 3, an idler roller 7a, and an idler roller 7b. Further, the image forming apparatus 100 includes an intermediate transfer belt 8, a tension roller 10, a transfer cleaner device 11, a resist roller 75, a secondary transfer inner roller 76, a secondary transfer outer roller 77, and a paper discharge roller 78. Furthermore, the image forming apparatus 100 includes a fixing unit 101, a louver 105, a door 112, an exhaust duct 114, a paper discharge roller 115, a transfer unit 120, a control unit 500, an in-body paper discharge unit 601, and a paper feeding unit 800.

[0016] The image forming unit PY forms a yellow (Y) toner image. The image forming unit PY includes a photosensitive drum 1Y, a charging member 2Y, a developing device 4Y, a primary transfer roller 5Y, and a photosensitive drum cleaner 6Y.

[0017] The photosensitive drum 1Y rotates in the R1 direction by a driving unit (not shown).

[0018] The charging member 2Y uniformly charges the surface of the photosensitive drum 1Y to a predetermined polarity and potential.

[0019] The developing device 4Y develops the electrostatic latent image formed on the photosensitive drum 1Y by the laser scanner unit 3 with toner to form a toner image on the photosensitive drum 1Y.

[0020] The primary transfer roller 5Y primarily transfers the toner image formed on the photosensitive drum 1Y by the developing device 4Y to the intermediate transfer belt 8.

[0021] The photosensitive drum cleaner 6Y removes the residual transferred toner remaining on the photosensitive drum 1Y after the primary transfer by the primary transfer roller 5Y from the photosensitive drum 1Y.

[0022] The image forming unit PM forms a magenta (M) toner image. The image forming unit PM comprises a photosensitive drum 1M, a charging member 2M, a developing device 4M, a primary transfer roller 5M, and a photosensitive drum cleaner 6M. The configurations of the photosensitive drum 1M, charging member 2M, and developing device 4M are the same as those of the photosensitive drum 1Y, charging member 2Y, and developing device 4Y, so their descriptions are omitted. Similarly, the configurations of the primary transfer roller 5M and photosensitive drum cleaner 6M are the same as those of the primary transfer roller 5Y and photosensitive drum cleaner 6Y, so their descriptions are omitted.

[0023] The image forming unit PC forms a cyan (C) toner image. The image forming unit PC comprises a photosensitive drum 1C, a charging member 2C, a developing device 4C, a primary transfer roller 5C, and a photosensitive drum cleaner 6C. The configurations of the photosensitive drum 1C, charging member 2C, and developing device 4C are the same as those of the photosensitive drum 1Y, charging member 2Y, and developing device 4Y, so their descriptions are omitted. Similarly, the configurations of the primary transfer roller 5C and photosensitive drum cleaner 6C are the same as those of the primary transfer roller 5Y and photosensitive drum cleaner 6Y, so their descriptions are omitted.

[0024] The image forming unit PK forms a black (K) toner image. The image forming unit PK comprises a photosensitive drum 1K, a charging member 2K, a developing unit 4K, a primary transfer roller 5K, and a photosensitive drum cleaner 6K. Note that the configurations of the photosensitive drum 1K, charging member 2K, and developing unit 4K are the same as those of the photosensitive drum 1Y, charging member 2Y, and developing unit 4Y, so their descriptions are omitted. Similarly, the configurations of the primary transfer roller 5K and photosensitive drum cleaner 6K are the same as those of the primary transfer roller 5Y and photosensitive drum cleaner 6Y, so their descriptions are omitted.

[0025] The laser scanner unit 3 irradiates the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K, which are uniformly charged by the charged members 2Y, 2M, 2C, and 2K, with laser light based on electrical signals transmitted from an image reading device or external device (not shown). By irradiating the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K with laser light, the laser scanner unit 3 sequentially exposes the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K, forming an electrostatic latent image on the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K.

[0026] The idler roller 7a, together with the idler roller 7b, tension roller 10, and secondary transfer inner roller 76, tensions the intermediate transfer belt 8.

[0027] The idler roller 7b, together with the idler roller 7a, tension roller 10, and secondary transfer inner roller 76, tensions the intermediate transfer belt 8.

[0028] The intermediate transfer belt 8 rotates in the R2 direction by a drive unit (not shown) to transport the toner image, which has been primary transferred from the photosensitive drums 1Y, 1M, 1C, and 1K by the primary transfer rollers 5Y, 5M, 5C, and 5K, to the transfer nip section T2.

[0029] The tension roller 10, together with the idler roller 7a, idler roller 7b, and secondary transfer inner roller 76, tensions the intermediate transfer belt 8.

[0030] The transfer cleaner device 11 removes any remaining transfer toner from the intermediate transfer belt 8 after it has passed through the transfer nip section T2.

[0031] The registration roller 75 corrects the skewness of the sheet material P fed from the paper feeding section 800 and transports the skew-corrected sheet material P to the transfer nip section T2.

[0032] The secondary transfer roller 76, together with the idler roller 7a, idler roller 7b, and tension roller 10, stretches the intermediate transfer belt 8.

[0033] The secondary transfer outer roller 77 contacts the secondary transfer inner roller 76 via the intermediate transfer belt 8, thereby forming a transfer nip portion T2.

[0034] The secondary transfer inner roller 76 and secondary transfer outer roller 77 grip the sheet material P being transported by the resist roller 75 at the transfer nip section T2 and apply a predetermined pressure to the sheet material P being transported by the resist roller 75. By gripping the sheet material P at the transfer nip section T2 and applying a predetermined pressure to the sheet material P, the secondary transfer inner roller 76 and secondary transfer outer roller 77 transfer the toner image that was primarily transferred to the intermediate transfer belt 8 to the sheet material P. The secondary transfer inner roller 76 and secondary transfer outer roller 77 transport the sheet material P, on which the toner image has been secondarily transferred, to the fixing section 101.

[0035] The paper discharge roller 78 discharges the sheet material P, which is conveyed by the paper discharge roller 115, to the paper discharge section 601 inside the cylinder.

[0036] The fixing unit 101 fixes the toner image on the sheet material P, which is conveyed by the secondary transfer inner roller 76 and the secondary transfer outer roller 77, by heating and pressurizing the toner image transferred to the sheet material P. The fixing unit 101 then conveys the sheet material P with the toner image fixed to it to the paper discharge roller 115. The fixing unit 101 includes an endless belt 107, a pressure roller 108, and a heater 109.

[0037] The endless belt 107 and the pressure roller 108 come into contact with each other to form a fixing nip section T3. The endless belt 107 and the pressure roller 108 grip and transport the sheet material P at the fixing nip section T3, thereby applying heat and pressure to the sheet material P and fixing the toner image that has been secondarily transferred to the sheet material P.

[0038] The heater 109 heats the endless belt 107.

[0039] The louver 105 is installed on the door 112 and communicates the inside of the exhaust duct 114 to the outside. The louver 105 allows air containing water vapor to be discharged from the exhaust duct 114 to the outside of the image forming apparatus 100. The louver 105 is set to discharge the air containing water vapor in a desired direction, such as the rear or side of the image forming apparatus 100.

[0040] The door 112 is provided on the side surface 100a of the image forming apparatus 100. The door 112 opens and closes by rotating in the front-to-back direction. However, the door 112 is not limited to opening and closing by rotating in the front-to-back direction; it may also be a retractable type.

[0041] The exhaust duct 114 is located between the fixing section 101 and the door 112. The exhaust duct 114 is responsible for collecting UFPs and discharging water vapor from the image forming apparatus 100 to the outside. Details of the configuration of the exhaust duct 114 will be described later.

[0042] The paper discharge roller 115, which serves as a conveying member, has a paper discharge nip section T4 formed by a pair of rollers contacting each other. The paper discharge roller 115 grips the sheet material P conveyed by the fixing section 101 at the paper discharge nip section T4 and conveys it to the paper discharge roller 78.

[0043] The control unit 500 controls the overall operation of the image forming apparatus 100.

[0044] The sheet material P discharged by the paper discharge roller 78 is placed in the paper discharge section 601 inside the cylinder.

[0045] The paper feeding unit 800 stores the sheet material P and feeds the stored sheet material P to the register roller 75 via the transport path 74. The paper feeding unit 800 includes a paper feeding cassette 72 and a paper feeding roller 73.

[0046] The paper feed cassette 72 is located at the bottom of the image forming apparatus 100. The sheet material P is stored in the paper feed cassette 72.

[0047] The paper feed roller 73 feeds the sheet material P contained in the paper feed cassette 72 one sheet at a time to the register roller 75 via the transport path 74.

[0048] The image forming apparatus 100 having the above configuration stores images input by an image input means (not shown), such as a connected personal computer, and secondarily transfers the toner image formed in the image forming units PY, PM, PC, and PK, which use an electrophotographic process, onto a sheet material P.

[0049] Furthermore, in the image forming apparatus 100, the paper feeding section 800 is positioned below the paper discharge roller 78 in the direction of gravity, and the sheet material P is conveyed upward from the paper feeding section 800. <Exhaust duct configuration> The configuration of the exhaust duct 114 of the image forming apparatus 100 according to Embodiment 1 of the present invention will be described in detail with reference to Figures 2 and 3.

[0050] In Figure 3, Figure 3(a) is a cross-sectional view of section AA in Figure 2, and Figure 3(b) is a cross-sectional view of section BB in Figure 2.

[0051] The exhaust duct 114 includes a filter 102, a fan 103, a first intake section 104a, a second intake section 104b, and an exhaust port 111.

[0052] As shown in Figure 3(a), the filter 102 extends along the width direction perpendicular to the conveying direction of the sheet material P (hereinafter simply referred to as the "conveying direction") and along the longitudinal direction of the secondary transfer outer roller 77. The longitudinal width W1 of the filter 102 is preferably greater than or equal to the maximum width of the sheet material P that can be passed through, since UFP is generated from the entire image forming area of ​​the fixing nip T3. Here, a width W1 of 300 mm is used as an example.

[0053] The filter 102 is located on the side of the first intake section 104a to the intake port 104c, which will be described later, and collects (filters) UFP from the air drawn in through the intake port 104c. When collecting UFP caused by wax, it is desirable that the filter 102 be made of electrostatic nonwoven fabric.

[0054] Electrostatic nonwoven fabric filters have a structure in which statically charged fibers are formed on a nonwoven fabric, and can filter UFPs with high efficiency. While higher fiber density leads to higher filtration performance, it also tends to increase pressure loss. This relationship holds true even when the thickness of the electrostatic nonwoven fabric is increased. Furthermore, increasing the electrostatic charge strength (strength of static electricity) of the fibers can improve filtration performance while maintaining a constant pressure loss. It is desirable to appropriately set the thickness of the electrostatic nonwoven fabric, fiber density, and electrostatic charge strength of the fibers according to the required filtration performance of the filter 102.

[0055] The fan 103 generates a flow from the intake port 104c of the first intake section 104a and the intake port 104d of the second intake section 104b toward the exhaust port 111, thereby forcibly exhausting the air around the fixing nip section T3 to the outside of the image forming apparatus 100.

[0056] The first intake section 104a is located on the opposite side of the exhaust port 111 from the fan 103. The first intake section 104a has an intake port 104c at the end opposite to the exhaust port 111. The intake port 104c is located between the fixing nip section T3 and the transfer nip section T2 in the vertical direction and draws in air. The first intake section 104a is mainly provided to collect UFP, a substance generated inside the image forming apparatus 100 by heating toner containing a release agent, using a filter 102.

[0057] The second intake part 104b is provided on the side opposite to the exhaust port 111 with respect to the fan 103. The second intake part 104b includes an air intake port 104d at the end on the side opposite to the exhaust port 111 side. The air intake port 104d is located between the fixing nip part T3 and the paper discharge nip part T4 of the paper discharge roller 115 in the vertical direction and sucks air. The second intake part 104b is provided to discharge the water vapor generated inside the image forming apparatus 100 to the outside of the image forming apparatus 100. The longitudinal width W2 of the second intake part 104b is preferably the width of the maximum size through which the sheet material P can pass, as shown in FIG. 3(b), since the moisture contained in the sheet material P becomes water vapor. The width W2 is exemplified as 300 mm here.

[0058] The exhaust port 111 is provided between the fan 103 and the louver 105, and the first intake part 104a and the second intake part 104b communicate with the outside of the image forming apparatus 100 via the louver 105.

[0059] <UFP Generation Mechanism> The UFP generation mechanism in the image forming apparatus 100 according to Embodiment 1 of the present invention will be described in detail.

[0060] In the fixing unit 101, a high-temperature endless belt 107 is brought into contact with the sheet material P to fix the toner image. At this time, an offset phenomenon may occur in which a part of the toner transfers (adheres) to the endless belt 107, and if such an offset phenomenon occurs, it may cause image defects. Therefore, measures against the offset phenomenon are essential. [[ID=<<MASK_E>>16]]

[0061] As the above measure, toner containing wax as a release agent is used. The toner containing wax is configured such that the wax melts and bleeds out when heated. Thus, the surface of the endless belt 107 of the fixing unit 101 is covered with the wax melted by the fixing process, making it difficult for the toner to adhere.

[0062] Here, the term "wax" includes not only pure wax but also compounds containing the molecular structure of wax. Compounds containing the molecular structure of wax are, for example, compounds formed by the reaction of toner resin molecules with wax molecular structures such as hydrocarbon chains. Furthermore, in addition to wax, other substances with release properties, such as silicone oil, may be used as release agents.

[0063] When wax melts, some of it vaporizes (volatilizes). This is thought to be because there is variation in the size of the molecular components contained in the wax. In other words, wax contains low molecular weight components with short chains and low boiling points, and high molecular weight components with long chains and high boiling points, and it is thought that the low molecular weight components with low boiling points vaporize first. Then, when the vaporized (gasified) wax components cool in the air, UFPs, which are fine particles ranging from a few nanometers to several hundred nanometers in size, are generated (it is presumed that most of the generated particles have a particle size of a few nanometers to tens of nanometers).

[0064] UFP is most abundant in the fixing nip section T3 where heat is applied to the wax. Furthermore, due to the rotation direction of the endless belt 107 and the arrangement of the heater 109, the upstream side of the fixing nip section T3 in the transport direction becomes the hottest. Consequently, UFP generation is also greatest on the upstream side of the fixing nip section T3 in the transport direction. Moreover, since UFP is generated from the toner image transferred to the sheet material P, it is generated from the entire image forming area of ​​the fixing nip section T3.

[0065] <Mechanism of water vapor generation> The water vapor generation mechanism in the image forming apparatus 100 according to Embodiment 1 of the present invention will be described in detail.

[0066] The sheet material P is heated and pressurized in the fixing nip section T3 of the fixing section 101. During this process, water vapor is generated from the moisture contained in the sheet material P. Since the water vapor generated from the sheet material P is generated immediately after the sheet material P is heated in the fixing section 101, it is mainly generated on the downstream side in the transport direction of the fixing nip section T3.

[0067] <Exhaust duct operation> The operation of the exhaust duct 114 of the image forming apparatus 100 according to Embodiment 1 of the present invention will be described in detail with reference to Figures 2 and 3.

[0068] In the fixing nip section T3 of the fixing section 101, the toner image that has been secondarily transferred to the sheet material P is heated, generating UFP from the toner in the toner image. The UFP generated in this way is drawn in through the intake port 104c of the first intake section 104a by the flow generated by the fan 103 of the exhaust duct 114 and heads towards the exhaust port 111.

[0069] UFPs heading towards the exhaust port 111 are collected by the filter 102. This ensures reliable collection of UFPs in situations where UFPs are likely to be generated due to the heating of the sheet material P by the endless belt 107, which has a high surface temperature.

[0070] Furthermore, when the sheet material P is heated in the fixing nip T3 of the fixing section 101, the moisture contained in the sheet material P evaporates and water vapor is generated. The water vapor generated in this way is drawn in mainly from the intake port 104d of the second intake section 104b and heads toward the exhaust port 111 by the flow generated by the fan 103, and also drawn in from the intake port 104c of the first intake section 104a and heads toward the exhaust port 111.

[0071] The water vapor directed toward the exhaust port 111 is discharged to the outside of the image forming apparatus 100 via the exhaust port 111 and the louvers 105.

[0072] In this embodiment, the exhaust duct 114 includes a first intake section 104a and a second intake section 104b. The first intake section 104a is located between the transfer nip section T2 and the fixing nip section T3 and includes an intake port 104c for drawing in air and a filter 102. The second intake section 104b is located between the fixing nip section T3 and the paper discharge roller 115 and includes an intake port 104d for drawing in air. This allows UFP to be collected without increasing the size of the device, and water vapor to be properly discharged to the outside of the image forming apparatus 100.

[0073] In this embodiment, the filter 102 is provided on the intake port 104c side of the first intake section 104a, but the filter 102 is not limited to this and can be provided at any position on the first intake section 104a.

[0074] Furthermore, in this embodiment, a door 112 is provided on the right side surface 100a of the image forming apparatus 100 in Figure 1. However, the invention is not limited to this, and a door 112 may also be provided on the left side surface of the image forming apparatus 100 in Figure 1. In this case, the exhaust duct 114 is provided on the left side of the image forming apparatus 100 in Figure 1.

[0075] Furthermore, in this embodiment, the first intake section 104a is made straight along the left-right direction, but the invention is not limited to this, and the first intake section 104a may also be made curved.

[0076] Furthermore, in this embodiment, the second intake section 104b is made straight in both the left-right and up-down directions, but the invention is not limited to this, and the second intake section 104b may also be made curved.

[0077] (Embodiment 2) The configuration of the image forming apparatus according to Embodiment 2 of the present invention is the same as that shown in Figure 1, so its description will be omitted.

[0078] <Exhaust duct configuration> The configuration of the exhaust duct 214 of the image forming apparatus according to Embodiment 2 of the present invention will be described in detail with reference to Figures 4 and 5.

[0079] In Figure 5, Figure 5(a) is a cross-sectional view of the CC section of Figure 4, and Figure 5(b) is a cross-sectional view of the DD section of Figure 4.

[0080] In addition, parts in Figures 4 and 5 that have the same configuration as those in Figures 2 and 3 are denoted by the same reference numerals, and their descriptions are omitted.

[0081] The exhaust duct 214 includes a filter 102, a fan 103, an exhaust port 111, a first intake section 204a, and a second intake section 204b.

[0082] The filter 102 is located on the exhaust port 111 side of the first intake section 204a. As shown in Figure 5(a), the filter 102 extends along the front-to-back direction, which is the longitudinal direction of the secondary transfer outer roller 77. The filter 102 is located on the intake port 204c side of the first intake section 204a, and collects (filters) UFP from the air drawn in from the intake port 204c.

[0083] The fan 103 generates a flow from the intake port 204c of the first intake section 204a and the intake port 204d of the second intake section 204b toward the exhaust port 111, thereby forcibly exhausting the air around the fixing nip section T3 to the outside of the image forming apparatus 100.

[0084] The exhaust port 111 is located between the fan 103 and the louver 105, and connects the first intake section 204a and the second intake section 204b to the outside of the image forming apparatus 100 via the louver 105.

[0085] The first intake section 204a is located on the opposite side of the exhaust port 111 from the fan 103. The first intake section 204a has an intake port 204c at the end opposite to the exhaust port 111. The intake port 204c is located between the fixing nip section T3 and the transfer nip section T2 in the vertical direction and draws in air. The first intake section 204a is mainly provided to collect UFP, a substance generated inside the image forming apparatus 100 by heating the toner containing a release agent, using the filter 102.

[0086] The second intake section 204b is located on the opposite side of the exhaust port 111 from the fan 103. The second intake section 204b has an intake port 204d at the end opposite to the exhaust port 111. The intake port 204d is located between the fixing nip section T3 and the paper discharge nip section T4 of the paper discharge roller 115 in the vertical direction and draws in air. The second intake section 204b is provided to discharge water vapor generated inside the image forming apparatus 100 to the outside of the image forming apparatus 100. The longitudinal width W2 of the second intake section 204b is preferably the width of the maximum size through which the sheet material P can be passed, as shown in Figure 5(b), because the moisture contained in the sheet material P turns into water vapor.

[0087] The opening height A2 of the second intake section 204b is smaller than the opening height A1 of the first intake section 204a (A1 > A2). Here, the opening height A1 of the first intake section 204a is exemplified as 30 mm. Here, the opening height A2 of the second intake section 204b is exemplified as 10 mm. Also, here, the width A3 of the second intake section 204b on the fan 103 side is exemplified as 40 mm.

[0088] <Exhaust duct operation> The operation of the exhaust duct 214 of the image forming apparatus according to Embodiment 2 of the present invention will be described in detail with reference to Figures 4 to 7.

[0089] Generally, the pressure loss through the filter 102 is greater than the pressure loss through the exhaust duct 214. Therefore, the amount of intake air drawn in through the second intake section 204b, which does not have a filter 102, is greater than the amount of intake air drawn in through the first intake section 204a, which has a filter 102. Consequently, the intake air volume Q1 drawn into the first intake section 204a becomes smaller than the intake air volume Q2 drawn into the second intake section 204b (Q1 <Q2)。

[0090] For example, if the opening height A1 is 30 mm and the width W1 is 300 mm, and the opening height A2 is 30 mm and the width W2 is 300 mm, the intake airflow rate Q1 will be 0.001 m³ / min and the intake airflow rate Q2 will be 0.69 m³ / min. In this case, the intake airflow rate Q1 becomes smaller than the intake airflow rate Q2.

[0091] Here, there are two ways to increase the intake airflow rate Q1. The first is to use a filter 102 with a smaller thickness or fiber density of electrostatic nonwoven fabric, thereby reducing the pressure loss in the first intake section 204a. However, if a filter with a smaller thickness or fiber density of electrostatic nonwoven fabric is used, the UFP collection capacity will decrease.

[0092] The second method is to increase the ratio of the amount of air drawn from the first intake section 204a to the amount of air drawn from the second intake section 204b by increasing the pressure loss of the second intake section 204b. When the pressure loss of the second intake section 204b is increased, it becomes more difficult to draw air in from the second intake section 204b, while it becomes easier to draw air in from the first intake section 204a.

[0093] Generally, the pressure loss P of a duct can be calculated from the following equation (1).

[0094] P = ξ·γ·(V^2) / 2 =ξ·γ·((Q / 60A)^2) / 2 (1) However, ξ is the duct-specific loss coefficient. γ is the density of the gas. V is wind speed (m / s) Q is the intake airflow rate (m³ / min). A is the cross-sectional area of ​​the duct (m²).

[0095] As can be seen from equation (1), the pressure loss in a duct increases as the cross-sectional area of ​​the duct decreases.

[0096] In this embodiment, when the opening heights A1 and A2 are the same size, the intake airflow Q2 of the second intake section 204b is sufficiently large because the filter 102 is not provided. On the other hand, when the opening heights A1 and A2 are the same size, the intake airflow Q1 of the first intake section 204a is only a gentle breeze because the filter 102 is provided. The amount of UFP generated varies depending on the configuration of the fuser section 101 and the toner material. Therefore, when the amount of UFP generated increases, it is necessary to increase the intake airflow Q1 in order to improve the UFP collection capacity.

[0097] Therefore, in this embodiment, in order to increase the pressure loss of the second intake section 204b, the opening height A2 of the second intake section 204b is made smaller than the opening height A1 of the first intake section 204a (A1 > A2).

[0098] Figure 7(a) shows the change in intake airflow rate Q1 when the opening height of the second intake section 204b is changed. Figure 7(b) also shows the change in intake airflow rate Q2 in the same case. Figures 7(a) and 7(b) show the changes in intake airflow rate Q1 and intake airflow rate Q2 when the opening height A2 is the same as the opening height A1, 30 mm, and when the opening height A2 is 30 mm and also smaller than the opening height A1, 10 mm.

[0099] As shown in Figure 7(a), the intake airflow rate Q1 when the opening height A2 is 10 mm is 3.5 times higher than the intake airflow rate Q1 when the opening height A2 is 30 mm. Therefore, it can be seen that the UFP collection capacity is higher when the opening height A2 is 10 mm compared to when the opening height A2 is 30 mm.

[0100] On the other hand, as shown in Figure 7(b), the intake air volume Q2 when the opening height A2 is 10 mm is 0.9 times lower than the intake air volume Q2 when the opening height A2 is 30 mm. However, since the second intake section 204b does not have a filter 102, the intake air volume Q2 is inherently large, making it possible to exhaust water vapor sufficiently.

[0101] Furthermore, since the operation of the exhaust duct 214 other than those described above is the same as the operation of the exhaust duct 114, the explanation for that operation will be omitted.

[0102] According to this embodiment, by making the opening height A2 of the second intake section 204b smaller than the opening height A1 of the first intake section 204a, in addition to the effects of the first embodiment described above, it is possible to suppress a decrease in the intake air volume Q1.

[0103] In this embodiment, the overall opening height A2 of the second intake section 204b is reduced, but the invention is not limited to this, and the opening height of only a part of the second intake section 204b may also be reduced. Specifically, as shown in Figure 8(a), the same effect can be obtained by reducing the opening height A2 of only a part of the second intake section 204b.

[0104] Furthermore, in this embodiment, the opening height A2 is made smaller than the opening height A1, but this is not the only way to change it. As long as the cross-sectional area of ​​the second intake section 204b can be made smaller than the cross-sectional area of ​​the first intake section 204a, other parameters besides the opening height may also be changed. For example, as shown in Figure 8(b), the same effect can be obtained by reducing the width A3 of the second intake section 204b instead of the opening height A2 of the second intake section 204b.

[0105] Furthermore, in this embodiment, a door 112 is provided on the right side surface 100a of the image forming apparatus 100 in Figure 1. However, the invention is not limited to this, and a door 112 may also be provided on the left side surface of the image forming apparatus 100 in Figure 1. In this case, the exhaust duct 214 is provided on the left side of the image forming apparatus 100 in Figure 1.

[0106] Furthermore, in this embodiment, the first intake section 204a is made straight along the left-right direction, but the invention is not limited to this, and the first intake section 204a may also be made curved.

[0107] Furthermore, in this embodiment, the second intake section 204b is made straight in both the left-right and up-down directions, but the invention is not limited to this, and the second intake section 204b may also be made curved.

[0108] (Embodiment 3) The configuration of the image forming apparatus according to Embodiment 3 of the present invention is the same as that shown in Figure 1, so its description will be omitted.

[0109] <Exhaust duct configuration> The configuration of the exhaust duct 314 of the image forming apparatus according to Embodiment 3 of the present invention will be described in detail with reference to Figure 9.

[0110] In Figure 9, parts that have the same configuration as those in Figure 2 are denoted by the same reference numerals, and their descriptions are omitted.

[0111] The exhaust duct 314 includes a filter 102, a fan 103, an exhaust port 111, a first intake section 304a, and a second intake section 304b.

[0112] The filter 102 is located on the side of the first intake section 304a to the intake port 304c, which will be described later, and collects (filters) UFP from the air drawn in through the intake port 304c.

[0113] The fan 103 generates a flow from the intake port 304c of the first intake section 304a and the intake port 304d of the second intake section 304b toward the exhaust port 111, thereby forcibly exhausting the air around the fixing nip section T3 to the outside of the image forming apparatus 100.

[0114] The exhaust port 111 is located between the fan 103 and the louver 105, and the first intake section 304a and the second intake section 304b communicate with the outside of the image forming apparatus 100 via the louver 105.

[0115] The first intake section 304a is located on the opposite side of the exhaust port 111 from the fan 103. The first intake section 304a has an intake port 304c at the end opposite to the exhaust port 111. The intake port 304c is located between the fixing nip section T3 and the transfer nip section T2 in the vertical direction and draws in air. The first intake section 304a is mainly provided to collect UFP, a substance generated inside the image forming apparatus 100 by heating toner containing a release agent, using the filter 102.

[0116] The second intake section 304b is located on the opposite side of the exhaust port 111 from the fan 103. The second intake section 304b has an intake port 304d at the end opposite to the exhaust port 111. The intake port 304d is located between the fixing nip section T3 and the paper discharge nip section T4 of the paper discharge roller 115 in the vertical direction and draws in air. The second intake section 304b is provided to discharge water vapor generated inside the image forming apparatus 100 to the outside of the image forming apparatus 100. The longitudinal width W2 of the second intake section 304b is preferably the width of the maximum size through which the sheet material P can pass, since the moisture contained in the sheet material P turns into water vapor.

[0117] The exhaust path length (L2+L3) of the second intake section 304b is set to be longer than the exhaust path length L1 of the first intake section 304b (L1<(L2+L3)). Here, L1 is the lateral distance from the intake port 304c of the first intake section 304a to the center of the fan 103. L2 is the lateral distance from the intake port 304d of the second intake section 304b to the wall portion 314a of the exhaust duct 314 which extends vertically. L3 is the vertical distance from the upper end of the wall portion 314a of the exhaust duct 314 to the center of the fan 103. The exhaust path length L1 is the length of the airflow path of the air drawn in at the first intake section 304a. The exhaust path length (L2+L3) is the length of the airflow path of the air drawn in at the second intake section 304b.

[0118] <Exhaust duct operation> The operation of the exhaust duct 314 of the image forming apparatus according to Embodiment 3 of the present invention will be described in detail with reference to Figure 9.

[0119] When the length of the exhaust duct 314 is L and the width of the exhaust duct 314 is D, the duct-specific loss coefficient ξ in equation (1) is proportional to L / D. In other words, the pressure loss of the exhaust duct 314 increases as the length of the exhaust duct 314 increases.

[0120] In this embodiment, by setting the exhaust path length (L2 + L3) of the second intake section 304b to be longer than the exhaust path length L1 of the first intake section 304b, the pressure loss of the second intake section 304b can be increased.

[0121] Furthermore, since the operation of the exhaust duct 314 other than those described above is the same as the operation of the exhaust duct 114, the explanation for that operation will be omitted.

[0122] According to this embodiment, by making the exhaust path length (L2 + L3) of the second intake section 304b longer than the exhaust path length L1 of the first intake section 304a, in addition to the effects of the first embodiment described above, it is possible to suppress a decrease in the intake air volume Q1.

[0123] In this embodiment, a door 112 is provided on the right side surface 100a of the image forming apparatus 100 in Figure 1. However, the door 112 may also be provided on the left side surface of the image forming apparatus 100 in Figure 1. In this case, the exhaust duct 314 is provided on the left side of the image forming apparatus 100 in Figure 1.

[0124] Furthermore, in this embodiment, the first intake section 304a is made straight along the left-right direction, but the invention is not limited to this, and the first intake section 304a may also be made curved.

[0125] Furthermore, in this embodiment, the second intake section 104b is made straight in both the left-right and up-down directions, but the invention is not limited to this, and the second intake section 104b may also be made curved.

[0126] (Embodiment 4) <Configuration of an image forming apparatus> The configuration of the image forming apparatus 200 according to Embodiment 4 of the present invention will be described in detail with reference to Figures 10 and 11.

[0127] In Figure 11, Figure 11(a) is a cross-sectional view of the EE section of Figure 10, and Figure 11(b) is a cross-sectional view of the FF section of Figure 10.

[0128] In Figures 10 and 11, parts that have the same configuration as those in Figures 2 and 3 are denoted by the same reference numerals, and their descriptions are omitted. Similarly, in the configuration of the image forming apparatus 200, parts that have the same configuration as those in the image forming apparatus 100 are omitted from both the illustration and the description.

[0129] The image forming apparatus 200 is exemplified here as a laser printer. The image forming apparatus 200 includes an image forming unit PY, an image forming unit PM, an image forming unit PC, an image forming unit PK, a laser scanner unit 3, an idler roller 7a, an idler roller 7b, an intermediate transfer belt 8, and a tension roller 10. The image forming apparatus 200 also includes a transfer cleaner unit 11, a registration roller 75, a secondary transfer inner roller 76, a secondary transfer outer roller 77, a paper discharge roller 78, and a fixing unit 101. Furthermore, the image forming apparatus 200 includes a louver 105, a door 112, a paper discharge roller 115, a transfer unit 120, an exhaust duct 414, a control unit 500, an internal paper discharge unit 601, and a paper feeding unit 800.

[0130] The louver 105 is provided on the rear cover 106 which constitutes the rear of the image forming apparatus 200, and communicates the inside of the exhaust duct 414 to the outside. The louver 105 allows water vapor to be discharged from the exhaust duct 414 to the outside of the image forming apparatus 200.

[0131] The exhaust duct 414 is located between the fixing unit 101 and the rear cover 106, which is provided on the rear of the image forming apparatus 200. The exhaust duct 414 collects UFP and discharges water vapor to the outside of the image forming apparatus 100.

[0132] <Exhaust duct configuration> The configuration of the exhaust duct 414 of the image forming apparatus according to Embodiment 4 of the present invention will be described in detail with reference to Figures 10 and 11.

[0133] The exhaust duct 414 includes a filter 102, a fan 103, an exhaust port 111, a first intake section 404a, and a second intake section 404b.

[0134] The filter 102 is located on the side of the first intake section 404a to the intake port 404c, which will be described later, and collects (filters) UFP from the air drawn in from the intake port 404c. As shown in Figure 11(a), the filter 102 extends along the front-to-back direction, which is the longitudinal direction of the secondary transfer outer roller 77.

[0135] The fan 103 generates a flow from the intake port 404c of the first intake section 404a and the intake port 404d of the second intake section 404b toward the exhaust port 111, thereby forcibly exhausting the air around the fixing nip section T3 to the outside of the image forming apparatus 200.

[0136] The exhaust port 111 is located between the fan 103 and the louver 105, and connects the first intake section 404a and the second intake section 404b to the outside of the image forming apparatus 200 via the louver 105.

[0137] The first intake section 404a is located on the opposite side of the exhaust port 111 from the fan 103. The first intake section 404a has an intake port 404c at the end opposite to the exhaust port 111. The intake port 404c is located between the fixing nip section T3 and the transfer nip section T2 in the vertical direction and draws in air. The first intake section 404a is mainly provided to collect UFP, a substance generated inside the image forming apparatus 200 by heating the toner containing a release agent, using the filter 102.

[0138] The second intake section 404b is located on the opposite side of the exhaust port 111 from the fan 103. The second intake section 404b has an intake port 404d at the end opposite to the exhaust port 111. The intake port 404d is located between the fixing nip section T3 and the paper discharge nip section T4 of the paper discharge roller 115 in the vertical direction and draws in air. The second intake section 404b is provided to discharge water vapor generated inside the image forming apparatus 200 to the outside of the image forming apparatus 200. The longitudinal width W2 of the second intake section 404b is preferably the width of the maximum size through which the sheet material P can pass, since the moisture contained in the sheet material P turns into water vapor.

[0139] Since the operation of exhaust duct 414 is the same as that of exhaust duct 114, its explanation will be omitted.

[0140] In this embodiment, an exhaust duct 414 is provided between the fixing unit 101 and the rear cover 106 on the back of the image forming apparatus 200. This allows water vapor generated from the sheet material P to be discharged to the back side of the image forming apparatus 200, in addition to the effects of Embodiment 1 described above.

[0141] In this embodiment, the first intake section 404a and the second intake section 404b are provided on the right side of the transport path 74 in the left-right direction. However, the invention is not limited to this configuration, and as shown in Figures 12 and 13, the first intake section 404a and the second intake section 404b may also be provided on the left side of the transport path 74 in the left-right direction.

[0142] Furthermore, in this embodiment, the first intake section 404a is made straight along the left-right and front-back directions, respectively, but the invention is not limited to this, and the first intake section 404a may also be made curved.

[0143] Furthermore, in this embodiment, the second intake section 404b is made straight in the left-right direction, the up-down direction, and the front-back direction, but the invention is not limited to this, and the second intake section 404b may also be made curved.

[0144] (Embodiment 5) <Configuration of an image forming apparatus> The configuration of the image forming apparatus according to Embodiment 4 of the present invention will be described in detail with reference to Figure 14.

[0145] In this embodiment, parts that have the same configuration as those of the image forming apparatus 100 in Embodiment 1 described above are given the same reference numerals, and their illustration and description are omitted.

[0146] The image forming apparatus according to this embodiment includes an image forming unit PY, an image forming unit PM, an image forming unit PC, an image forming unit PK, a laser scanner unit 3, an idler roller 7a, and an idler roller 7b. The image forming apparatus according to this embodiment also includes an intermediate transfer belt 8, a tension roller 10, a transfer cleaner device 11, a resist roller 75, a secondary transfer inner roller 76, a secondary transfer outer roller 77, a paper discharge roller 78, and a fixing unit 101. Furthermore, the image forming apparatus according to this embodiment also includes a louver 105, a door 112, a paper discharge roller 115, a transfer unit 120, an exhaust duct 514, a control unit 500, an internal paper discharge unit 601, and a paper feeding unit 800.

[0147] The louver 105 is provided on the rear cover 106 which constitutes the rear part of the image forming apparatus, and communicates the inside of the exhaust duct 514 to the outside. The louver 105 allows water vapor to be discharged from the exhaust duct 514 to the outside of the image forming apparatus.

[0148] The exhaust duct 514 is located between the fixing unit 101 and the rear cover 106, which is provided on the back of the image forming apparatus. The exhaust duct 514 collects UFP and discharges water vapor to the outside of the image forming apparatus.

[0149] <Exhaust duct configuration> The configuration of the exhaust duct 514 of the image forming apparatus according to Embodiment 5 of the present invention will be described in detail with reference to Figure 14.

[0150] In Figure 14, parts that have the same configuration as those in Figure 2 are denoted by the same reference numerals, and their descriptions are omitted.

[0151] The exhaust duct 514 includes a filter 102, a fan 103, an exhaust port 111, a first intake section 504a, and a second intake section 504b.

[0152] The filter 102 is located on the side of the first intake section 504a to the intake port 504c, which will be described later, and collects (filters) UFP from the air drawn in through the intake port 504c.

[0153] The fan 103 generates a flow from the intake port 504c of the first intake section 504a and the intake port 504d of the second intake section 504b toward the exhaust port 111, thereby forcibly exhausting the air around the fixing nip section T3 to the outside of the image forming apparatus.

[0154] The exhaust port 111 is located between the fan 103 and the louver 105, and the first intake section 504a and the second intake section 504b communicate with the outside of the image forming apparatus 100 via the louver 105.

[0155] The first intake section 504a is located on the opposite side of the exhaust port 111 from the fan 103. The first intake section 504a has an intake port 504c at the end opposite to the exhaust port 111. The intake port 104c is located between the fixing nip section T3 and the transfer nip section T2 in the vertical direction and draws in air. The first intake section 504a is mainly provided to collect UFP, a substance generated inside the image forming apparatus 200 by heating toner containing a release agent, using the filter 102.

[0156] The second intake section 504b is located on the opposite side of the exhaust port 111 from the fan 103. The second intake section 504b has an intake port 504d at the end opposite to the exhaust port 111. The intake port 504d is located between the fixing nip section T3 and the paper discharge nip section T4 of the paper discharge roller 115 in the vertical direction and draws in air. The second intake section 504b is provided to discharge water vapor generated inside the image forming apparatus 200 to the outside of the image forming apparatus 200. The longitudinal width W2 of the second intake section 504b is preferably the width of the maximum size through which the sheet material P can pass, since the moisture contained in the sheet material P turns into water vapor.

[0157] The opening height A12 of the second intake section 504b is smaller than the opening height A11 of the first intake section 504a (A11 > A12). Here, the opening height A11 of the first intake section 504a is exemplified as 30 mm. Here, the opening height A12 of the second intake section 504b is exemplified as 10 mm. Also, here, the width A13 of the second intake section 504b on the fan 103 side is exemplified as 40 mm.

[0158] The exhaust path length (L12 + L13) of the second intake section 504b is set to be longer than the exhaust path length L11 of the first intake section 504b (L11 < (L12 + L13)). Here, L11 is the left-right distance from the intake port 504c of the first intake section 504a to the center of the fan 103. L12 is the left-right distance from the intake port 504d of the second intake section 504b to the center of the fan 103. L13 is the vertical distance from the upper end of the inner wall surface 514a of the exhaust duct 514 to the center of the fan 103. The exhaust path length L11 is the length of the airflow path of the air taken in at the first intake section 504a. The exhaust path length (L12 + L13) is the length of the airflow path of the air taken in at the second intake section 504b.

[0159] Since the operation of exhaust duct 514 is the same as the operation of exhaust duct 214 or exhaust duct 314, its explanation will be omitted.

[0160] In this embodiment, an exhaust duct 414 is provided between the fixing unit 101 and the rear cover 106 on the back of the image forming apparatus. This allows water vapor generated from the sheet material P to be discharged to the rear side of the image forming apparatus 200, and also suppresses a decrease in the intake air volume Q1.

[0161] In this embodiment, the configuration satisfies all of the following conditions: the opening height A11 is greater than the opening height A12, the opening height A11 is greater than the width A13, and the intake path length L11 is greater than the intake path length (L12 + L13). However, the configuration is not limited to this, and any one or two of the above conditions may be satisfied.

[0162] Furthermore, in this embodiment, the overall opening height A12 of the second intake section 504b is reduced, but the embodiment is not limited to this, and the opening height of a part of the second intake section 504b may also be reduced.

[0163] Furthermore, in this embodiment, the opening height A12 is made smaller than the opening height A11, but the invention is not limited to this. As long as the cross-sectional area of ​​the second intake section 504b can be made smaller than the cross-sectional area of ​​the first intake section 504a, other parameters besides the opening height may also be changed. For example, the same effect can be obtained by reducing the width A13 of the second intake section 504b instead of the opening height A12 of the second intake section 504b.

[0164] Furthermore, in this embodiment, the first intake section 504a and the second intake section 504b are provided on the right side of the transport path 74 in the left-right direction. However, the invention is not limited to this, and the first intake section 504a and the second intake section 504b may also be provided on the left side of the transport path 74 in the left-right direction.

[0165] Furthermore, in this embodiment, the first intake section 504a is made straight along the left-right and front-back directions, respectively, but the invention is not limited to this, and the first intake section 504a may also be made curved.

[0166] Furthermore, in this embodiment, the second intake section 504b is made straight in the left-right direction, the up-down direction, and the front-back direction, but the invention is not limited to this, and the second intake section 504b may also be made curved.

[0167] The present invention is not limited to the embodiments described above, and it goes without saying that various modifications are possible without departing from the spirit of the invention.

[0168] Specifically, in Embodiments 1 to 5 described above, the filter 102 was a nonwoven fabric filter, but it is not limited to this, and the filter 102 may be a filter other than a nonwoven fabric filter, such as a honeycomb filter.

[0169] Furthermore, in Embodiments 1 to 5 described above, the width W1 was set to be greater than or equal to the maximum width of the sheet material P, but this is not limited to this, and the width W1 may be set to less than the maximum width of the sheet material P.

[0170] Furthermore, in Embodiments 1 to 5 described above, the width W2 was set to be greater than or equal to the maximum width of the sheet material P, but the invention is not limited to this, and the width W2 may be set to be less than the maximum width of the sheet material P.

[0171] Furthermore, in the above embodiments 1 to 5, the sheet material P was heated by an endless belt 107, but the sheet material P may also be heated by a heating roller or a belt unit in which a belt is stretched over a plurality of rollers.

[0172] Furthermore, in Embodiments 1 to 5 described above, the image forming apparatus was a laser printer, but it is not limited to this, and the image forming apparatus may be an inkjet printer or other type of printer. Here, although the inkjet method does not have a fuser that applies heat and pressure to the sheet material P, it has a drying unit, and therefore has the same problems as the heat dissipation and exhaust problems of the laser printer. [Explanation of Symbols]

[0173] PC image forming section PK image forming section PM image forming section PY image forming section T2 Transfer Nip Section T3 Fixing nip section T4 Paper output nip section 100 Image forming apparatus 101 Fixing section 102 filters 103 Fans 104a First intake section 104b Second intake section 104c air intake 104d Air intake 106 Back cover 107 Endless belt 108 Pressure Roller 111 Exhaust vent 112 Doors 114 Exhaust duct 115 Paper output roller 200 Image forming apparatus 204a First intake section 204b Second intake section 204c air intake 204d Air intake 214 Exhaust duct 304a First intake section 304b Second intake section 304c air intake 304d Air intake 404a First intake section 404b Second intake section 404c air intake 404d Air intake 414 Exhaust duct 504a First intake section 504b Second intake section 504c air intake 504d Air intake 514 Exhaust duct

Claims

1. An image forming apparatus for forming an image on a sheet material, An image forming unit that forms a toner image using toner, A transfer unit comprising a transfer nip section for transferring a toner image formed by the image forming unit onto a sheet material, The fixing unit includes a fixing nip section that heats the sheet material onto which the toner image has been transferred in the transfer nip section to fix the toner image to the sheet material, A transport member for transporting the sheet material on which the toner image has been fixed in the fixing nip section, An exhaust duct equipped with a filter, which draws in air from inside the image forming apparatus and exhausts it to the outside of the image forming apparatus, It has, The aforementioned exhaust duct is A first intake section comprising an air intake port located between the transfer nip section and the fixing nip section and for drawing in air, and a filter, A second intake section is located between the fixing nip section and the conveying member and is equipped with an air intake port for drawing in air. Equipped with, Image forming apparatus characterized by

2. The cross-sectional area of ​​the second intake section is, Smaller than the cross-sectional area of ​​the first intake section, The image forming apparatus according to feature 1.

3. The length of the airflow path in the second intake section is: A length longer than the length of the airflow path of the intake air in the first intake section, The image forming apparatus according to claim 1 or 2.

4. The aforementioned filter is This device collects substances generated when the release agent contained in the toner is heated. The image forming apparatus according to claim 1 or 2.

5. The aforementioned filter is It is installed extending in the width direction perpendicular to the conveying direction of the sheet material. The image forming apparatus according to claim 1 or 2.

6. The aforementioned exhaust duct is The fixing unit is provided between the side surface of the image forming apparatus, Image forming apparatus according to claim 1 or 2

7. The aforementioned exhaust duct is The fixing unit is provided between the rear surface of the image forming apparatus, The image forming apparatus according to claim 1 or 2.

Images