Image forming apparatus

Abstract

An imaging apparatus includes: an imaging section; a fixing portion configured to fix the toner image onto a recording material; a housing accommodating the image forming portion and the fixing portion, in which a transport path through which the recording material passes is formed; and a discharge portion configured to discharge the recording material. The housing includes a first outer surface and a second outer surface. The second outer surface is provided with an opening portion through which the exterior of the housing and the interior of the housing communicate with each other. The image forming apparatus further includes a filter disposed to cover the opening portion. In a width direction perpendicular to both the vertical direction and the discharge direction, a center of the transport path is located between one end and the other end of a range in which the opening portion is provided.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus for forming an image on a recording material. Background Art

[0002] Japanese Patent Application Laid-Open No. H09-281825 discloses that an opening portion (discharge port) for discharging water vapor generated in a fixing portion to the outside of the apparatus is provided in a top cover of an image forming apparatus.

[0003] There is a possibility that dust enters the interior of the image forming apparatus through an opening portion provided in a housing of the apparatus. Summary of the invention

[0004] The present invention provides an imaging device capable of reducing dust entry.

[0005] According to one aspect of the present invention, an imaging device includes: an imaging portion configured to form a toner image on a recording material; a fixing portion configured to form a clamping portion to clamp the recording material, and configured to fix the toner image to the recording material by heating the toner image while conveying the recording material with the clamping portion; a housing that accommodates the imaging portion and the fixing portion and forms a conveying path through which the recording material passes; and a discharge portion configured to discharge the recording material to the outside of the housing in a discharge direction that intersects a vertical direction, wherein the housing includes a first outer surface and a second outer surface , a first outer surface faces a discharge direction and is provided with a discharge port, and the recording material discharged by the discharge portion passes through the discharge port, a second outer surface faces a direction opposite to the discharge direction and is provided with an opening portion, the outside of the shell and the inside of the shell are connected to each other through the opening portion, wherein at least a portion of the discharge port and at least a portion of the opening portion are located above the upper end position of the clamping portion in the vertical direction, wherein the imaging device also includes a filter arranged to cover the opening portion, and wherein in a width direction perpendicular to both the vertical direction and the discharge direction, the center of the conveying path is located between one end and the other end of the range where the opening portion is provided.

[0006] According to another aspect of the present invention, an imaging device includes: an imaging part, which is configured to form a colorant image on a recording material; a fixing part, which is configured to form a clamping part in which the recording material is clamped and heat the colorant image at the clamping part while conveying the recording material, thereby fixing the colorant image to the recording material; a shell, which accommodates the imaging part and the fixing part, and forms a conveying path through which the recording material passes; and a discharge part, which is configured to discharge the recording material to the outside of the shell in a discharge direction intersecting with the vertical direction, wherein the shell includes a first outer surface and a second outer surface, the first outer surface faces the discharge direction and is provided with a discharge port, and the recording material discharged by the discharge part passes through the discharge port, and the second outer surface faces the direction opposite to the discharge direction and is provided with an opening portion, the outside of the shell and the conveying path in the shell are connected to each other through the opening portion, wherein at least a portion of the discharge port and at least a portion of the opening portion are located above the upper end position of the clamping part in the vertical direction, and wherein the imaging device also includes a filter arranged to cover the opening portion.

[0007] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1A is a schematic diagram of an imaging device according to Example 1.

[0009] Figure 1B is a detailed view of an imaging device according to Example 1.

[0010] Figure 2 is a schematic diagram of an imaging device according to Example 1.

[0011] Figure 3A is a schematic diagram of an imaging device according to Example 1.

[0012] Figure 3B is a detailed view of an imaging device according to Example 1.

[0013] Figure 4A and Figure 4B is a schematic diagram of a discharge port according to Example 1.

[0014] Figure 5 is a schematic diagram showing a ventilation portion and a filter according to Example 1.

[0015] Figure 6 is a perspective view of a rear door according to Example 1.

[0016] Fig. 7A and Figure 7B is a schematic diagram illustrating air flow in an imaging apparatus according to Example 1.

[0017] Fig. 8A and Figure 8B is a schematic diagram illustrating air flow in an image forming apparatus according to Comparative Example 1.

[0018] Fig. 9A and Fig. 9B is an explanatory diagram of an experiment in which dust particles were allowed to enter an imaging device.

[0019] Fig.10 is a schematic diagram showing traces of water drops.

[0020] Fig.11 It is an explanatory diagram of the falling of dust particles when the rear door is opened and closed.

[0021] Fig.12 is a schematic diagram showing an image of black spots originating from dust particles.

[0022] Fig.13 is a perspective view of an imaging device according to Example 2.

[0023] Fig.14 is a diagram showing a state in which the exterior components of the imaging apparatus according to Example 2 are omitted.

[0024] FIG. 15A to FIG. 15C is an explanatory diagram of an exhaust fan according to Example 2.

[0025] Fig.16A and Fig. 16B is a schematic diagram illustrating air flow in an image forming apparatus according to Comparative Example 2.

[0026] Fig.17A and Fig. 17B is a schematic diagram illustrating air flow in an imaging apparatus according to Example 2.

[0027] Fig.18 is a schematic diagram showing a modified example.

[0028] Fig.19 is a schematic diagram showing a modified example. DETAILED DESCRIPTION

[0029] Embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0030] Example 1

[0031] In this example, the Figure 1AThe image forming apparatus 100 shown is used as an example to describe a configuration example of the image forming apparatus. The image forming apparatus 100 is a monochrome laser printer that forms a monochrome image by an electrophotographic system, and forms an image (toner image) on a recording material P by using a toner as a developer according to image information transmitted to the image forming apparatus from an external device such as a personal computer. As the recording material P (recording medium), various sheet materials of different materials can be used. Examples of the various sheet materials include: paper sheets such as ordinary paper sheets and cardboard; irregularly shaped sheets such as envelopes and index paper sheets; and cloth.

[0032] In the following description, when the imaging device 100 is set on a horizontal plane, the up and down direction (vertical direction, direction along the gravity direction) of the imaging device 100 will be referred to as the Z-axis direction. The direction of the rotation axis of the photosensitive drum 1 will be referred to as the X-axis direction. The direction intersecting both the X-axis direction and the Z-axis direction will be referred to as the Y-axis direction. The X-axis direction, the Y-axis direction and the Z-axis direction are preferably orthogonal to each other. In the X-axis direction, the positive side (+X side) will be referred to as the right side, and the negative side (-X side) will be referred to as the left side. In the Y-axis direction, the positive side (+Y side) will be referred to as the front side or the front surface side, and the negative side (-Y side) will be referred to as the rear side or the rear surface side. In the Z-axis direction, the positive side (+Z side) will be referred to as the upper side, and the negative side (-Z side) will be referred to as the lower side.

[0033] In this example, the X-axis direction is the width direction of the recording material P perpendicular to both the vertical direction of the recording material P and the discharge direction Dc.

[0034] Imaging equipment

[0035] Figure 1A and Figure 2 is a schematic diagram showing a cross section of an imaging apparatus 100 according to Example 1. Figure 1B yes Figure 1A Detailed view of the .

[0036] like Figure 1A , Figure 1B and Figure 2 As shown, the image forming apparatus 100 includes a feeding section 6, a registration roller pair 8, an image forming section 10, a fixing section 9, and an ejecting section 16. In addition, the image forming apparatus 100 includes a housing 101 that accommodates the feeding section 6, the registration roller pair 8, the image forming section 10, the fixing section 9, and the ejecting section 16.

[0037] The feeding section 6 includes: a stacking section (box, tray) which is attachable to and detachable from the housing 101 and on which the recording material P is stacked; and a roller pair 41 which feeds the recording material P one by one from the stacking section. The registration roller pair 8 conveys the recording material P fed by the feeding section 6 to the transfer nip Ntr at a timing matching the toner image formation in the image forming section 10. The image forming section 10 forms a toner image by performing an electrophotographic process, and transfers the toner image to the recording material P in the transfer nip Ntr, thereby forming an image on the recording material P. The fixing section 9 forms a fixing nip Nf serving as a clamping section for clamping the recording material P, and fixes the toner image to the recording material P by heating the toner image in the fixing nip Nf while conveying the recording material P. The discharge portion 16 discharges the recording material P on which the image has been formed to the outside of the image forming apparatus 100 (outside of the housing 101, outside of the housing) in a discharge direction Dc intersecting the vertical direction (Z-axis direction).

[0038] Figure 1A The arrow P1 in FIG. 1 indicates a conveyance path of the recording material P in the case where single-sided printing (single-sided image formation) is performed, in which case the image forming apparatus 100 forms an image only on one surface (first surface) of the recording material P. It should be noted that in the case where the image forming apparatus 100 performs double-sided printing (double-sided image formation) in which an image is formed on each of the first surface and the second surface opposite thereto of the recording material P, the recording material P is also conveyed along the path of the arrow P1 when an image is formed on the first surface. Figure 2 An arrow P2 indicates a conveying path in which the recording material P on the first surface of which image formation has been completed is conveyed toward the image forming portion 10 again in a case where the image forming apparatus 100 performs double-sided printing.

[0039] A series of operations in which the image forming apparatus 100 performs single-sided printing or double-sided printing while conveying one recording material P and discharges the recording material P to the outside of the image forming apparatus 100 will be referred to as an image forming operation or a sheet passing operation. An operation in which the image forming apparatus 100 continuously performs image forming operations (sheet passing operations) on a plurality of recording materials P will be referred to as continuous sheet passing. The cumulative sheet number of recording materials P represents the number of recording materials P on which the image forming apparatus 100 has performed image forming operations since the image forming apparatus 100 has been shipped from a factory or since the image forming apparatus 100 has been initialized after shipping, and the cumulative sheet number will be referred to as a cumulative sheet passing number.

[0040] In the present example, among the recording materials on which the imaging device 100 can form an image, the recording material having the maximum width in the X-axis direction (width direction) (recording material of the maximum size) is a recording material of LTR (letter) size (width: 215.9 mm). In addition, the maximum printing width is 206 mm, and the maximum printing width is the width of the area (effective printing area) on which the imaging part 10 can form an image on the LTR size recording material. In the present example, among the recording materials on which the imaging device 100 can form an image, the recording material having the minimum width in the X-axis direction (width direction) (recording material of the minimum size) is a recording material with a width of 98.4 mm. In other words, in the present example, the maximum sheet passing width of the imaging device 100 is 215.9 mm, and the minimum sheet passing width is 98.4 mm.

[0041] That is, in this example, in the recording material on which the imaging device can form an image, in the width direction perpendicular to both the vertical direction and the discharge direction, the passing area of ​​the recording material with the largest size having the maximum length in the X-axis direction (width direction) is an area with a width of 215.9 mm. In addition, in this example, the passing area of ​​the recording material with the smallest size in the width direction is an area with a width of 98.4 mm. In this example, the passing area of ​​the recording material extends symmetrically with respect to the center of the conveying path CP in the X-axis direction (width direction). The center of the conveying path CP refers to the center of the space through which the recording material P can pass, and may be located Figure 4A The center position in the X-axis direction between the two rubber roller portions 81a at both ends of the discharge driving roller 81 is shown. In addition, in the case where the positioning portions for positioning the two end portions of the recording material P in the X-axis direction are provided on the stacking portion of the feeding portion 6, the center of the conveying path CP may be the center position between the positioning portions of the two end portions in the X-axis direction.

[0042] Furthermore, assuming that an image is formed on an A4-size paper sheet with an image coverage of 4%, the life sheet number of the image forming apparatus 100 (the cumulative sheet passing number defining the life of the image forming apparatus 100) is, for example, 50,000.

[0043] The housing 101 includes a frame body of the imaging device 100 and an external member (cover member or door member) serving as an outer surface of the imaging device 100. A rear door 14 and an ejection tray 17 to be described later are each an example of an external member. The space on the outside relative to the outer surface of the housing 101 will be referred to as the outside of the imaging device 100 or the outside of the device, and the space on the inside relative to the outer surface of the housing 101 will be referred to as the inside of the imaging device 100 or the inside of the device. Inside the imaging device 100, a conveying path CP serving as a passage space through which a recording material P passes is provided.

[0044] The housing 101 of this example is provided with an inlet port 6s, a discharge port 16s, and a ventilation portion 51. The inlet port 6s, the discharge port 16s, and the ventilation portion 51 are each an opening portion including an opening through which the interior of the imaging device 100 communicates with the exterior of the imaging device 100. More specifically, the inlet port 6s, the discharge port 16s, and the ventilation portion 51 are each an opening portion through which the conveying path CP communicates with the exterior of the imaging device 100. The inlet port 6s is an opening portion (feed port) through which the recording material P fed by the feeding portion 6 is received. The discharge port 16s is an opening portion through which the recording material P discharged by the discharge portion 16 passes. The ventilation portion 51 will be described later.

[0045] In this example, the inlet port 6s and the outlet port 16s are each an opening, and the ventilation portion 51 includes a plurality of openings (a plurality of ventilation holes 51a to be described later). A plurality of inlet ports 6s and / or a plurality of outlet ports 16s may be provided. The ventilation portion 51 may be configured to include only one opening. In addition, the housing 101 may have an opening different from the above-mentioned openings.

[0046] The conveying path Cp includes a main conveying path CP1 and a double-sided conveying path CP2. The main conveying path CP1 is a conveying path extending from the inlet port 6s via the transfer nip Ntr and the fixing nip Nf to the discharge port 16s. The double-sided conveying path CP2 is a conveying path that branches from the main conveying path CP1 at a position between the fixing section 9 and the discharge section 16 in the recording material conveying direction in the main conveying path CP1 and merges with the main conveying path CP1 at a position between the roller pair 41 of the feed section 6 and the registration roller pair 8.

[0047] In other words, the conveying path CP includes a main conveying path CP1 serving as a first conveying path through which a recording material passes when the image forming section 10 forms an image on the recording material P. Further, the conveying path CP includes a duplex conveying path CP2 serving as a second conveying path that branches from the first conveying path and through which, in the case where an image is formed on a second surface of the recording material opposite to the first surface, the recording material on the first surface of which a toner image has been formed by the image forming section 10 is again conveyed toward the image forming section 10.

[0048] The image forming section 10 includes a photosensitive drum 1 serving as an image bearing member, a charging roller 2 serving as a charging section, a scanner unit 4 serving as an exposure section, a developing unit 3 serving as a developing section, a transfer roller 5 serving as a transfer unit, and a pre-exposure unit 23. The developing unit 3 includes a toner container 32 containing a toner T serving as a developer, and a developing roller 31 that carries the toner in the toner container 32 and thus supplies the toner to the photosensitive drum 1. A transfer nip Ntr serving as a transfer section for image transfer is formed between the photosensitive drum 1 and the transfer roller 5.

[0049] Part or all of the imaging portion 10 may be a cartridge that is attachable to and detachable from the housing 101. In this case, for example, the housing 101 may include a cover member that is openably and closably provided on its front surface or upper surface, and the cartridge may be attached and detached by opening the cover member.

[0050] The photosensitive drum 1 is a photosensitive member formed in a cylindrical shape (drum shape). The photosensitive drum 1 of this example includes a photosensitive layer formed of a negatively chargeable organic photosensitive material on a drum-shaped substrate formed of aluminum or the like. More specifically, the photosensitive drum 1 is formed by applying a resistive layer, a primer layer, and a photosensitive layer in sequence on the peripheral surface of an aluminum cylinder with a diameter of 24 mm serving as a substrate by a dip coating method. The photosensitive drum 1 is a member that basically has high rigidity. The photosensitive layer includes a charge generating layer that generates charges in response to the incidence of light, and a charge transport layer that transports the generated charges. The film thickness of the charge transport layer is, for example, 22 μm.

[0051] The photosensitive drum 1 is rotationally driven about its rotation axis in the direction of arrow R1 at a predetermined peripheral speed by a driving source not shown. The peripheral speed of the photosensitive drum 1 defines the image forming speed of the image forming apparatus 100 and is also called the process speed. The process speed of this example is, for example, 140 mm / sec.

[0052] The charging roller 2 contacts the photosensitive drum 1 with a predetermined contact pressure, thereby forming a charging portion. In this example, the contact portion (nipping portion) between the charging roller 2 and the photosensitive drum 1 in the rotation direction of the photosensitive drum 1 is about 1 mm. The charging roller 2 includes a conductive substrate. Since the charging power supply applies a predetermined charging voltage to the conductive substrate, the charging roller 2 uniformly charges the surface of the photosensitive drum 1 to a predetermined potential. In this example, the photosensitive drum 1 is negatively charged by the charging roller 2.

[0053] The charging roller 2 used in this example includes a core metal having a diameter of 5 mm as a conductive substrate, a base layer formed of alcohol rubber, and a surface layer formed of polyurethane, and is formed to have an outer diameter of 9.7 mm. In addition, the resistance of the charging roller 2 is 1×10 6 Ω or less, and its hardness measured by the MD-1 rubber hardness meter is 70°. It should be noted that although a DC voltage is used as the charging voltage in this example, the configuration is not limited thereto, and the charging voltage may be a voltage in which an AC voltage is superimposed on a DC voltage.

[0054] The core metal is provided with a gear, and the charging roller 2 rotates at a constant speed relative to the photosensitive drum 1 due to the engagement of the gear with the gear of the photosensitive drum 1. In this example, the gear ratio and the like are set so that the peripheral speed ratio between the charging roller 2 and the photosensitive drum 1 is about 107% in the image formation. The peripheral speed ratio between the charging roller 2 and the photosensitive drum 1 is the ratio of the surface speed of the charging roller 2 to the surface speed of the photosensitive drum 1. In the charging portion, due to the speed difference between the charging roller 2 and the photosensitive drum 1, the toner attached to the charging roller 2 may be returned to the photosensitive drum 1 by friction charging.

[0055] In this example, a pressure spring is used that presses the charging roller 2 toward the photosensitive drum 1. The pressure spring presses the bearings that support the core metal portion at both ends of the charging roller 2 in the charging portion in a direction perpendicular to the surface of the photosensitive drum 1. In the rotation axis direction of the photosensitive drum 1 (X-axis direction), the pressure on the side on which the gear of the charging roller 2 is provided, that is, the pressure on the drive side is 7.5N, and the pressure on the opposite side of the gear, that is, the pressure on the non-drive side is 5.6N.

[0056] In order to generate stable discharge in the charged portion, the pre-exposure unit 23 irradiates a region of the surface of the photosensitive drum 1 after passing through the transfer nip Ntr and before reaching the charged portion with light to remove residual charge.

[0057] Scanner unit 4 irradiates photosensitive drum 1 with laser light corresponding to image information input from an external device by using a polygon mirror, thereby exposing the surface of photosensitive drum 1 in a scanning manner. An electrostatic latent image corresponding to the image information is formed on the exposed surface of photosensitive drum 1.

[0058] The developing unit 3 supplies toner T to the photosensitive drum 1, thereby developing the electrostatic latent image into a toner image. In this example, a contact developing method is adopted as a developing method, and the toner layer carried on the developing roller 31 contacts the photosensitive drum 1 at a developing portion where the photosensitive drum 1 and the developing roller 31 are opposite to each other. A developing voltage is applied to the developing roller 31 by a developing power source. Due to the electric field formed at the developing roller 31 by the developing voltage, the toner carried on the developing roller 31 is transferred from the developing roller 31 to the drum surface according to the potential distribution on the surface of the photosensitive drum 1. As a result, the electrostatic latent image on the photosensitive drum 1 is visualized as a toner image.

[0059] A polymer toner formed by a polymerization method can be used as the toner T of this example. The normal charging polarity (standard polarity) of the toner T is negative. In addition, the toner particle diameter is 6 μm.

[0060] The transfer roller 5 is pressed against the photosensitive drum 1 by a predetermined pressure, thereby forming a transfer nip Ntr. The transfer roller 5 rotates by following the rotating photosensitive drum 1 or following the recording material P passing through the transfer nip Ntr. A positive polarity voltage is applied from a transfer power source not shown to the core metal of the transfer roller 5. According to the electric field generated by the applied voltage, the toner image carried on the photosensitive drum 1 is transferred onto the recording material P at the transfer nip Ntr.

[0061] The transfer roller 5 used in this example includes a core metal of a nickel-plated steel rod, and a foam sponge layer mainly formed of nitrile rubber (NBR) and epichlorohydrin rubber on the outer peripheral surface of the core metal. The diameter of the core metal is 8 mm, and the thickness of the foam sponge layer is 3 mm. In addition, as a result of the bearings holding both ends of the core metal being pushed by the spring member, the transfer roller 5 is in pressure contact with the photosensitive drum 1 by a pressure of 1 kgf (9.8 N).

[0062] In this example, a cleaner-less system (drum-less cleaner system, simultaneous development-cleaning system) is adopted in which the toner (transfer residual toner) remaining on the photosensitive drum 1 that has not been transferred to the recording material P at the transfer nip Ntr is collected by the developing unit 3. The transfer residual toner is charged to a negative polarity by the charging roller 2 at the charging portion. The development voltage is set so that the surface potential of the developing roller 31 relative to the non-image portion of the photosensitive drum 1 is at a positive polarity. Therefore, the transfer residual toner attached to the non-image portion is transferred from the photosensitive drum 1 to the developing roller 31 at the developing portion, and is collected by the developing unit 3. The collected transfer residual toner is stirred together with the toner T contained in the toner container 32, and is used again for development.

[0063] In the drum-less cleaner system, a cleaning member for removing transfer residual toner from the photosensitive drum 1 and a waste toner container for accommodating the removed transfer residual toner can be omitted. Therefore, the image forming apparatus can be miniaturized. It should be noted that, in addition to the configuration of this example, the image forming apparatus 100 may include a cleaning member and a waste toner container instead of the drum-less cleaner system.

[0064] The fixing portion 9 is a unit of a heat fixing system (image heating unit) that fixes the toner image onto the recording material P by heating the toner image. More specifically, the fixing portion 9 heats and presses the toner image on the recording material P while holding and conveying the recording material P to which the toner image has been transferred in the transfer nip Ntr in the fixing nip Nf. Thus, the toner particles melt and then adhere, and thereby the toner image is fixed to the recording material P.

[0065] The fixing part 9 of this example is a unit of a film heating system, which excels in shortening the startup time and reducing power consumption. The fixing part 9 includes a fixing film 112 used as a heating member (fixing member), a heater 113 used as a heating part, a heater holder 130 for holding the heater 113, and a pressure roller 110 used as a pressure member. The fixing film 112 is a tubular (annular) film with flexibility. The heater 113 is held by the heater holder 130 and is arranged in the internal space of the fixing film 112 together with the heater holder 130. The pressure roller 110 is arranged so that the fixing film 112 is between the pressure roller 110 and the heater 113. The fixing clamping portion Nf is formed as a contact portion (clamping portion) between the fixing film 112 and the pressure roller 110.

[0066] The pressure roller 110 is an elastic roller (rubber roller) including a core metal and an elastic layer. As a result of the bearings provided at both ends of the core metal being pushed by the pressure spring, the pressure roller 110 is in pressure contact with the heater 113 with the fixing film 112 located therebetween. It should be noted that a configuration may be adopted in which the heater holder 130 (or a supporting member supporting the heater holder 130, such as a metal support) is pushed toward the pressure roller 110 by the pressure spring.

[0067] A driving force is input from a driving source to a driving gear provided at a core metal end portion, and thus the pressure roller 110 rotates. The fixing film 112 rotates by following the rotation of the pressure roller 110 or following the recording material P passing through the fixing nip Nf.

[0068] A typical heater used in a heating unit of a film heating system may be used as the heater 113. For example, the heater 113 is a ceramic heater including a ceramic substrate and a heating resistor arranged in a series circuit on the substrate. Specifically, the heater 113 includes an alumina substrate having a width of 6 mm and a thickness of 1 mm, an Ag / Pd (silver palladium) heating resistor having a height of 10 μm applied on the surface of the substrate by screen printing, and a glass layer having a thickness of 50 μm used as a protective layer, the protective layer being formed to cover the heating resistor.

[0069] As the fixing film 112, a film having a multilayer structure can be used, in which different material layers are stacked in the thickness direction. The multilayer structure includes, for example, a base layer sliding on the heater 113, a surface layer in contact with the recording material P, and a conductive primer layer combining the base layer and the surface layer. The outermost layer in the surface layer is a release layer for suppressing surface contamination. The fixing film 112 of this example has such a circumference that the fixing film 112 has an outer diameter of 20 mm when formed into a cylindrical shape.

[0070] The base layer needs heat resistance to receive the heat of the heater 113, and also needs a certain strength to slide on the heater 113. As the material of the base layer, metals such as stainless steel (SUS) or nickel, or heat-resistant resins such as polyimide can be used. Metals are stronger than resins, so they can be made thinner, and in addition, they have higher thermal conductivity, and are therefore more likely to transfer the heat of the heater 113 to the surface layer. In contrast, the specific gravity of the resin is less than that of the metal, so the heat capacity is smaller and it is easier to be heated. In addition, a resin film can be formed by coating, and therefore it can be formed at a lower cost. In this example, polyimide resin is used as the base material of the fixing film 112. In addition, a carbon-based filler is added to the polyimide resin to improve thermal conductivity and strength. The thinner the base layer, the higher the heat transfer efficiency of the fixing film 112, but if the base layer is too thin, sufficient strength may not be obtained. The thickness of the base layer is preferably about 15 μm to about 100 μm, and is set to 60 μm in this example.

[0071] The conductive primer layer is formed of polyimide resin, fluororesin or the like, and its resistance is reduced by adding carbon or the like. Preferably, the potential of the fixing film 112 during image formation is stabilized by electrically connecting (grounding) the exposed portion of the conductive layer to a ground potential.

[0072] As the material of the outermost layer (release layer), fluororesin, such as perfluoroalkoxy resin (PFA), polytetrafluoroethylene resin (PTFE) or tetrafluoroethylene-hexafluoropropylene resin (FEP) is preferably used. In this example, PFA with excellent release and heat resistance in fluororesin is used, and the resistance value of PFA is adjusted (to medium resistance) by dispersing a conductive agent in the matrix of PFA. The release layer can be formed by covering the peripheral surface of the base layer and the conductive primer layer with a tube, or can be formed by coating the surface of the conductive primer layer with a coating. In this example, the release layer is formed by a coating method, and the release layer can be formed thinner using this method. The thinner the release layer, the higher the heat transfer efficiency of the fixing film 112, but if the release layer is too thin, the durability of the fixing film 112 may be lower. The thickness of the release layer is preferably about 5 μm to about 30 μm, and is set to 10 μm in this example.

[0073] The pressure roller 110 of this example includes, for example, a core metal having an outer diameter of 9 mm and formed of iron, and an elastic layer having a thickness of 2.5 mm and formed of silicone rubber located on the outer peripheral side of the core metal. The elastic layer is formed of silicone rubber or fluororubber having heat resistance. The outer diameter of the pressure roller 110 is preferably about 10 mm to about 50 mm. The smaller the outer diameter of the pressure roller 110, the smaller the heat capacity, but if the outer diameter is too small, the width of the fixing nip Nf is small, so there is a possibility that the toner image is not sufficiently heated and the fixing of the toner image is deteriorated. In this example, the outer diameter of the pressure roller 110 is set to 14 mm. When the elastic layer is thin, the heat capacity can also be suppressed, but if the elastic layer is too thin, the heat may be dissipated to the core metal formed of metal, resulting in a decrease in the overall thermal efficiency of the fixing portion 9, so an appropriate thickness is required.

[0074] A release layer that enhances the release property of the toner can be provided on the peripheral surface of the elastic layer of the pressure roller 110. In this example, a release layer formed by a perfluoroalkoxy resin (PFA) is provided. Similar to the release layer of the fixing film 112, the release layer can be formed by covering the surface with a tube or coating the surface with a coating, and in this example, a release layer formed by a tube having a thickness of 20 μm and excellent durability is used. As the material of the release layer, a fluororesin such as PTFE or FEP, a fluororubber with high release property, a silicone rubber or the like can be used instead of PFA. When the surface hardness of the pressure roller 110 is low, a larger width of the fixing nip Nf can be obtained at a lower pressure, but if the surface hardness is too low, the durability will be reduced. In terms of Asker-C hardness (load: 600g), the surface hardness of the pressure roller 110 of this example is set to 40°.

[0075] A temperature detection element 115, such as a thermistor, for detecting the temperature of the heater 113 is provided on the rear surface of the heater 113. The controller of the image forming apparatus 100 controls the power supply to the heating resistor according to the output signal of the temperature detection element 115, thereby controlling the heating amount of the heater 113 so that the heater 113 is at a predetermined target temperature (adjustment temperature). The controller controls the heating amount of the heater 113 so that the surface temperature of the fixing film 112 at the fixing nip Nf is maintained at a temperature suitable for fixing the toner image. In the case of using ordinary paper as the recording material P, the adjustment temperature of the fixing portion 9 is, for example, 180°C.

[0076] The discharge section 16 is a conveying unit (discharge unit) that discharges the recording material P on which the image formation has been completed to the outside of the housing 101. The discharge section 16 includes a discharge roller pair consisting of a discharge drive roller 81 and a discharge driven roller 82. The discharge drive roller 81 is a drive roller that rotates by receiving a driving force from a driving source, and the discharge driven roller 82 is a driven roller that forms a nip portion with the discharge drive roller 81 and rotates by following the discharge drive roller 81.

[0077] The discharge portion 16 is provided inside or near a discharge port 16s of the housing 101. The discharge portion 16 clamps and conveys the recording material P in the discharge direction Dc by the discharge drive roller 81 and the discharge driven roller 82, thereby discharging the recording material P from the inside to the outside of the housing 101 through the discharge port 16s. A discharge tray 17 on which the recording material P discharged by the discharge portion 16 is stacked is provided on the upper surface of the housing 101.

[0078] In the case of single-sided printing, the recording material P having passed through the fixing nip Nf is directly discharged from the discharge portion 16 through the discharge port 16s. Figure 1A In the case of double-sided printing, Figure 2As shown, after the rear end of the recording material P in the discharge direction Dc has passed through the fixing nip Nf, the discharge drive roller 81 is rotationally driven in the direction opposite to the rotation direction following the discharge direction Dc, and the conveying direction of the recording material P is reversed. That is, the recording material P on which an image has been formed on its first surface while being conveyed in the main conveying path CP1 is turned back at the discharge portion 16 and conveyed to the double-sided conveying path CP2. In other words, in this example, the discharge portion 16 serves as a reverse conveying portion for reversing the recording material P in the case of double-sided printing. It should be noted that in addition to the discharge portion 16, a reverse conveying roller pair serving as a reverse conveying portion for reversing the recording material P may be provided. The recording material P conveyed along the double-sided conveying path CP2 is conveyed to the main conveying path CP1 again in a state where its first surface and second surface are switched. Then, while the recording material P is conveyed again in the main conveying path CP1, an image is formed on the second surface of the recording material P, and the recording material P is discharged by the discharge portion 16 through the discharge port 16s.

[0079] Duplex transport path

[0080] The double-sided conveying path CP2 will be described. Figure 2 As shown, the double-sided conveying path CP2 is defined by the double-sided guide 13, the double-sided rib 42, the U-shaped guide 43, etc. In other words, the housing 101 includes the double-sided guide 13, the double-sided rib 42, and the U-shaped guide 43. The double-sided guide 13, the double-sided rib 42, and the U-shaped guide 43 are each an example of a guide member that defines a portion of the conveying path CP (a portion of the double-sided conveying path CP2).

[0081] In this example, the main conveying path CP1 extends generally in the vertical direction from the feed portion 6 toward the discharge portion 16. The double-sided conveying path CP2 extends in the Y-axis direction in the direction opposite to the discharge direction Dc (toward the -Y side), and extends downward in the vertical direction (toward the -Z side) from the branch portion of the main conveying path CP1. The double-sided conveying path CP2 merges with the main conveying path CP1 via a U-shaped curved portion that is curved so that the double-sided conveying path CP2 curves upward in the vertical direction (toward the +Z side) while extending in the Y-axis direction toward the same side (+Y side) as the discharge direction Dc.

[0082] The duplex guide 13 defines a portion of the duplex transport path CP2 (an upstream portion of the duplex transport path CP2). The duplex guide 13 is an example of a guide member (a second guide portion) that defines a second transport path. The duplex guide 13 guides the first surface of the recording material P.

[0083] The double-sided guide 13 has a shape that is bent to have a convex shape that convexes upward when viewed from the direction of the rotation axis of the photosensitive drum 1 (X-axis direction). In other words, the upper surface of the double-sided guide 13 (second guide portion) is bent to have a convex shape that convexes upward when viewed from the width direction (X-axis direction) that is orthogonal to both the vertical direction and the discharge direction Dc. When viewed from the X-axis direction (width direction), the double-sided guide 13 (second guide portion) is located between the discharge port 16s and the ventilation portion 51 (opening portion) of the housing 101 in a direction (Y-axis direction) perpendicular to the vertical direction.

[0084] The double-sided rib 42 is part of the rear door 14 ( Figure 6 ). The double-sided rib 42, together with the guide portion 15a (Figure 3) of the transfer guide unit 15, defines a portion of the double-sided conveying path CP2 (a portion extending downward in the vertical direction). That is, the guide portion 15a of the transfer guide unit 15 is an example of a relative portion that is opposite to the inner surface 14b of the external member (rear door 14) with a gap therebetween. In addition, the guide portion 15a is an example of a first guide portion that is opposite to the inner surface 14b of the external member (rear door 14) and defines a portion of the conveying path CP together with the external member (rear door 14). In other words, the gap (space) provided between the inner surface 14b and the guide portion 15a is a portion of the conveying path CP (a portion of the double-sided conveying path CP2) through which the recording material P passes. It can be said that the space continuous with the gap provided between the inner surface 14b and the guide portion 15a is connected to the outside of the housing 101 through the ventilation portion 51. It should be noted that the upper end portion of the double-sided rib 42 in this example is opposed to the double-sided guide 13 , and is curved according to the curved shape of the double-sided guide 13 when viewed in the X-axis direction.

[0085] The double-sided rib 42 includes a plurality of rib shapes 42a ( Figure 6 ). The rib shapes 42a each protrude inward (toward the +Y side) in the housing 101 relative to the inner surface 14b of the rear door 14, and extend approximately in the Z-axis direction. That is, the rear door 14 has a rib shape that protrudes from the inner surface 14b in a direction approaching the first guide portion (the guide portion 15a of the transfer guide unit 15) and extends in the recording material conveying direction in the conveying path. The double-sided rib 42 contacts the recording material P on the ridge line portion (the end surface on the +Y side) of the rib shape 42a, and guides the second surface of the recording material P.

[0086] The U-shaped guide 43 defines a curved portion of the double-sided transport path CP2. The U-shaped guide 43 guides the first surface of the recording material P.

[0087] Jam removal

[0088] In a case where a jam has occurred in which the recording material P is stagnant in the image forming apparatus 100 during printing, the user may perform so-called jam removal, ie, remove the stagnant recording material P from the inside of the image forming apparatus 100 .

[0089] like Figure 3A and Figure 3B As shown, a housing 101 of the image forming apparatus 100 includes a rear door 14 and a transfer guide unit 15. The rear door 14 and the transfer guide unit 15 are each an opening / closing member that is openably and closably disposed relative to other parts of the housing 101. In the case where a user performs jam removal, the rear door 14 and the transfer guide unit 15 are opened and closed.

[0090] The housing 101 of the image forming apparatus 100 includes a rear door 14 and a transfer guide unit 15. The rear door 14 is an exterior member (rear cover) having an outer surface 14a serving as an outer surface (second outer surface) on the rear side (-Y side) of the housing 101.

[0091] The rear door 14 can be moved to an open position ( Figure 3A and Figure 3B ) and a closed position in which the body opening 101a is closed ( Figure 1A and Figure 1B ). The rear door 14 of the present example pivots around an axis extending in the X-axis direction around a hinge portion 141 provided at a lower end portion of the rear door 14 positioned in the closed position. When the rear door 14 is in the closed position, the recording material P can pass through the double-sided conveying path CP2. That is, the closed position of the rear door 14 is a position when the imaging device 100 can perform an imaging operation. When the rear door 14 is in the open position, at least a portion of the double-sided conveying path CP2 is opened, so that the recording material P stagnant in the double-sided conveying path CP2 can be approached from the outside of the housing 101. In other words, in a state in which the rear door 14 serving as an external member is located in the open position, it is allowed to remove the recording material P from a portion of the conveying path CP (double-sided conveying path CP2) through the main body opening 101a.

[0092] The transfer guide unit 15 includes a guide portion 15a, which defines a portion of the double-sided transport path CP2 together with the double-sided ribs 42 of the rear door 14 and the above-mentioned transfer roller 5. The transfer guide unit 15 is arranged between the rear door 14 and the photosensitive drum 1. More specifically, the transfer guide unit 15 is arranged between the photosensitive drum 1 and a gap (space) arranged between the inner surface 14b and the guide portion 15a. In the vertical direction, the transfer guide unit 15 is located below the ventilation portion 51, and the upper end of the transfer guide unit 15 is located above the photosensitive drum 1.

[0093] The transfer guide unit 15 is movable to a closed position (blocking position, Figure 1A and Figure 1B ) and an open position (exposed position, Figure 3A and Figure 3B ). The transfer guide unit 15 of this example pivots around a hinge portion 151 provided at a lower end portion of the transfer guide unit 15 located in the closed position around an axis extending in the X-axis direction. The position of the hinge portion 151 may be referred to as the position of the rotation axis of the transfer guide unit 15. In the vertical direction, the position of the rotation axis of the transfer guide unit 15 is located above the ventilation portion 51 and the photosensitive drum 1.

[0094] When the transfer guide unit 15 is in the closed position, the recording material P can pass through the main conveying path CP1. That is, the closed position of the transfer guide unit 15 is a position when the image forming apparatus 100 can perform an image forming operation. When the rear door 14 is in the open position and the transfer guide unit 15 is in the open position, at least a portion of the main conveying path CP1 is opened, so that the recording material P stagnant in the main conveying path CP1 can be accessed from the outside of the housing 101.

[0095] The transfer guide unit 15 of this example is urged by a spring member in a direction from the open position toward the closed position. By urging the transfer guide unit 15 by the spring member, the contact pressure between the transfer roller 5 and the photosensitive drum 1 can be more stabilized.

[0096] In the case where the recording material P is stagnant in the main transport path CP1, as shown in FIG. Figure 3A and Figure 3B As shown, the user opens the rear door 14 and the transfer guide unit 15 . Figure 3A and Figure 3B 1 is a schematic diagram and a detailed diagram showing jam removal in a case where the recording material P has not successfully passed through the fixing portion 9 and is stagnant in the main transport path CP1. The user can grab and remove the recording material P stagnant in the main transport path CP1 by opening both the rear door 14 and the transfer guide unit 15. Then, the user closes the rear door 14 and the transfer guide unit 15 again, and thus the image forming apparatus 100 returns to a state in which an image forming operation can be performed.

[0097] like Figure 2As shown, in duplex printing, when the recording material P passes through the duplex transport path CP2, a paper jam may occur. In this case, it is sufficient if the user only opens the rear door 14. By opening the rear door 14, the user can grab and remove the recording material P stagnant in the duplex transport path CP2. Then, the user closes the rear door 14 again, and thus the image forming apparatus 100 returns to a state in which an image forming operation can be performed.

[0098] Exhaust

[0099] Reference Figure 4A and Figure 4B The configuration of the discharge port 16s of the present example will be described. Figure 4A is a schematic diagram showing the discharge portion 16 of the present example viewed from the front side (+Y side) of the image forming apparatus 100, and Figure 4B yes Figure 4A Detailed drawing of.

[0100] In this example, the discharge port 16s is provided on the wall surface 101f ( Figure 1A and Figure 1B ) and is an opening through which the recording material P discharged by the discharge portion 16 passes. In other words, the housing 101 includes a wall surface 101f serving as a first outer surface facing the discharge direction Dc, and is provided with a discharge port 16s through which the recording material P discharged by the discharge portion 16 passes. It should be noted that the wall surface 101f extends upward from the upstream end of the discharge tray 17 in the discharge direction Dc, and serves as a standard surface for aligning the recording material P by abutting against the rear end of the recording material P stacked on the discharge tray 17.

[0101] More specifically, in the present example, when the imaging device 100 is viewed from the front side (+Y side), the discharge port 16s is an opening defined in the wall surface 101f of the housing 101 and extending to the inside of the imaging device 100. In the present example, the conveying path CP, which is the space inside the imaging device 100, and the space outside the imaging device 100 are connected to each other through the discharge port 16s.

[0102] Here, the configuration of the discharge portion 16 will be described. It is preferred that at least one of the rollers in the roller pair for clamping and conveying a sheet such as a recording material P is a split roller including a plurality of rotating members (a driving roller portion and a driven roller portion) each in contact with the recording material P. The split roller is a roller including a plurality of rotating members each having a width smaller than a maximum width of the recording material P serving as a conveying target in a width direction of the recording material P orthogonal to a discharge direction Dc of the recording material P, and in which a plurality of rotating members are arranged in the width direction. As a result of using the split roller, a situation in which the rollers in the roller pair do not contact each other or the contact pressure becomes insufficient in a partial region in the width direction due to warping of the rollers becomes less likely to occur, and thus the recording material P can be conveyed more stably.

[0103] Each of the rollers in the roller pair for pinching and conveying the sheet material may be a split roller. The discharge portion 16 of the present example is a roller pair including a discharge drive roller 81 and a discharge driven roller 82, each of which is a split roller.

[0104] The discharge drive roller 81 includes a shaft 81b extending in the width direction and a plurality of rubber roller parts 81a serving as a plurality of rotating members. In this example, four rubber roller parts 81a are attached to one shaft 81b. A drive gear is provided at the end of the shaft 81b, and a driving force is input to the shaft from a driving source via the drive gear. As a result of the driving force being input to the shaft 81b, the shaft 81b and the four rubber roller parts 81a rotate integrally.

[0105] The discharge driven roller 82 includes a plurality of roller parts 82a used as a plurality of rotating members, a plurality of roller retainers 82b that maintain the roller part 82a, and a plurality of springs 82c that push the roller retainer 82b. The discharge driven roller 82 of this example includes four roller parts 82a used as a plurality of rotating members, four roller retainers 82b that maintain the roller part 82a, and four springs 82c corresponding to the four rubber roller parts 81a of the discharge drive roller 81. The roller part 82a is rotatably supported by a corresponding roller retainer in the roller retainer 82b. In addition, since each roller retainer 82b is pushed by a corresponding spring in the spring 82c, the roller part 82a corresponding to it is in pressure contact with a corresponding rubber roller part in the rubber roller part 81a. Each roller part 82a rotates by following a corresponding rubber roller part in the rubber roller part 81a.

[0106] In four areas separated from each other in the width direction, there are formed nipped portions where the rubber roller portion 81a of the discharge drive roller 81 contacts the roller portion 82a of the discharge driven roller 82. The discharge portion 16 nipped the recording material P in the above-mentioned nipped portions, and conveyed the recording material P in the discharge direction Dc by the rotational drive of the discharge drive roller 81.

[0107] Since the discharge portion 16 has the above-described configuration, the region ( Figure 4A The discharge port 16s (shaded area of ​​​​the discharge drive roller 81) is defined in the opening 101h defined in the wall surface 101f of the housing 101. That is, in this example, when the image forming apparatus 100 is viewed from the front side (+Y side), the "discharge port 16s" is an area obtained by excluding portions such as the rubber roller portion 81a of the discharge drive roller 81 and the roller portion 82a of the discharge driven roller 82 (that is, a portion through which the recording material P cannot pass) from the area within the opening 101h provided in the wall surface 101f of the housing 101.

[0108] Ventilation section near the fixing section

[0109] The ventilation portion 51 serving as an opening portion, which is provided near the fixing portion 9 of the image forming apparatus 100, will be described. Figure 5 1 is a schematic diagram showing the ventilation portion 51 , and shows a cross section orthogonal to the X-axis direction of the rear door 14 provided with the ventilation portion 51 . Figure 6 is a perspective view of the rear door 14. It should be noted that Figure 5 Shown along Figure 6 In addition, as will be described later, since the filter 50 covering the ventilation portion 51 is provided, the position of each of the ventilation holes 51a of the ventilation portion 51 is determined by Figure 6 The dotted line in .

[0110] like Figure 5 As shown, the ventilation portion 51 includes at least one ventilation hole 51a serving as an opening through which the outside and the inside of the imaging device 100 communicate. More specifically, the outside of the imaging device 100 communicates with the conveying path CP (particularly the double-sided conveying path CP2 in this example) which is the internal space of the imaging device 100 through the ventilation hole 51a. The ventilation portion 51 of this example includes a plurality of ventilation holes 51a.

[0111] The ventilation hole 51a opens toward the outside of the image forming apparatus 100 in the outer surface 14a, which is a surface facing the direction (-Y direction) opposite to the discharge direction Dc of the rear door 14. In other words, the housing 101 includes the outer surface 14a serving as a second outer surface facing the direction opposite to the discharge direction Dc of the recording material P, and is provided with an opening portion (ventilation portion 51) through which the outside of the housing 101 and the conveying path CP through which the recording material P passes in the housing 101 communicate with each other.

[0112] In the image forming apparatus 100, heat is generated in the fixing portion 9, which belongs to the heat fixing system. When heat is accumulated in the image forming apparatus 100, there is a possibility that, for example, the temperature of the toner increases and thus the properties of the toner change or the aging of the components of the image forming apparatus 100 is accelerated. The ventilation portion 51 suppresses these problems by discharging the heat generated in the fixing portion 9 to the outside of the image forming apparatus 100.

[0113] Furthermore, in the fixing portion 9, water vapor is generated from the recording material P heated when passing through the fixing nip Nf. When the water vapor accumulates in the image forming apparatus 100, there is a possibility that, for example, water condensation occurs in the conveying path CP and thus water droplets adhere to the recording material P to cause image defects or accelerate the aging of components of the image forming apparatus 100 (rusting of metal members, etc.). The water vapor generated in the fixing portion 9 is discharged to the outside of the image forming apparatus 100 through the ventilation portion 51, so these problems are suppressed. In the Z-axis direction, the ventilation portion 51 is located above the photosensitive drum 1.

[0114] Heat and water vapor tend to move upward. Therefore, at least a portion of the ventilation portion 51 is located above the upper end position of the fixing nip Nf in the Z-axis direction ( Figure 1A In addition, at least a portion of the discharge port 16s is located above the upper end position of the fixing nip portion Nf in the Z-axis direction ( Figure 1A ). In other words, at least a portion of the discharge port 16s and at least a portion of the opening portion (ventilation portion 51) are located above the upper end position of the nip portion (fixing nip Nf) in the vertical direction.

[0115] The ventilation portion 51 of this example is arranged at the upper end portion of the outer surface 14a of the rear door 14, which constitutes the outer surface (second outer surface) of the rear side of the imaging device 100. In this example, the lower end position of the ventilation portion 51 is located above the upper end position of the fixing clamping portion Nf in the Z-axis direction. In addition, in this example, the lower end position of the discharge port 16s is located above the upper end position of the fixing clamping portion Nf in the Z-axis direction. It should be noted that the ventilation portion 51 can also be arranged in the top surface of the housing 101.

[0116] The range in which the ventilation portion 51 is set in the X-axis direction (width direction) will be referred to as the installation range of the ventilation portion 51 hereinafter. In the case where the ventilation portion 51 includes a plurality of ventilation holes 51a (a plurality of openings) arranged at different positions in the X-axis direction as in the present example, the installation range of the ventilation portion 51 can be defined as follows. That is, in the X-axis direction, the range from the farthest ventilation hole 51a1 (first opening) on ​​one side (+X side) in the X-axis direction among the plurality of ventilation holes 51a to the farthest ventilation hole 51a2 (second opening) on ​​the other side (-X side) in the X-axis direction is defined as the installation range of the ventilation portion 51. As Figure 6 As shown in FIG. 1 , in the X-axis direction, the installation range of the ventilation portion 51 overlaps with the position of the dotted line L. In other words, the dotted line L is located between one end (the position of the ventilation hole 51a1) and the other end (the position of the ventilation hole 51a2) of the installation range of the ventilation portion 51 in the X-axis direction. It should be noted that the position of the dotted line L in the X-axis direction coincides with the center position of the transport path CP in the X-axis direction and the center position of the passing area of ​​the recording material P in the X-axis direction.

[0117] In the fixing portion 9, heat for fixing the toner image is mainly generated in the passage area of ​​the recording material P in the X-axis direction (width direction). In addition, since water vapor is generated from the recording material P by heating the recording material P in the fixing nip Nf, water vapor is generated in the passage area of ​​the recording material P in the X-axis direction (width direction). Here, among the recording materials P on which the imaging device 100 can perform an imaging operation, the recording material P having the largest size in the X-axis direction (width direction) will be referred to as the recording material P of the largest size. Therefore, the installation range of the ventilation portion 51 preferably overlaps with the passage area of ​​the recording material P of the largest size in the X-axis direction (width direction). In this example, the installation range of the ventilation portion 51 overlaps with the passage area of ​​the recording material P of the LTR size, which is the maximum sheet passing width of the imaging device 100. As a result, the heat and water vapor generated in the fixing portion 9 can be effectively discharged to the outside of the imaging device 100.

[0118] In the X-axis direction (width direction), the length of the installation range of the ventilation portion 51 (the length of the installation range of the ventilation portion 51 from one end to the other end) is preferably 50% or more of the length of the conveying path CP, and more preferably 70% or more. In addition, in the X-axis direction, the length of the installation range of the ventilation portion 51 is preferably 50% or more of the length of the maximum size of the recording material P, and more preferably 70% or more. In addition, in the X-axis direction, it is preferred that the installation range of the ventilation portion 51 includes the range of the maximum width (effective printing area) on which the image forming portion 10 can form an image. In this example, in the X-axis direction (width direction), the length of the installation range of the ventilation portion 51 is 90% or more of the maximum size of the recording material P. Due to the above reasons, in the fixing portion 9, heat and water vapor are mainly generated in the passing area of ​​the recording material P. Therefore, as a result of providing the ventilation portion 51 within a predetermined ratio or more relative to the maximum size of the recording material P, the heat and water vapor generated in the fixing portion 9 can be effectively discharged to the outside of the imaging device 100.

[0119] Here, among the recording materials P on which the imaging device 100 can perform an imaging operation, the recording material P having the smallest size in the X-axis direction (width direction) will be referred to as the smallest-sized recording material P. The installation range of the ventilation portion 51 preferably includes at least the passage area of ​​the smallest-sized recording material P. That is, in the X-axis direction (width direction), the length of the installation range of the ventilation portion 51 is greater than the length of the smallest-sized recording material P. This is because regardless of the size of the recording material P, at least a portion of the recording material P on which an image is formed by the imaging device 100 always passes through the passage area of ​​the smallest-sized recording material P, and thus water vapor may be generated in the passage area of ​​the smallest-sized recording material P.

[0120] In a case where the air permeability of the ventilation portion 51 is high, the amount of heat and water vapor that can be discharged through the ventilation portion 51 is large, and thus the problem caused by the accumulation of heat and water vapor can be suppressed more reliably. However, if the air permeability of the ventilation portion 51 is too high, in a case where wind blows in from the front side (+Y side) of the imaging device 100, the wind speed from the exhaust port 16s through the conveying path CP and then through the ventilation portion 51 becomes high, and dust becomes more likely to enter. Therefore, the air permeability of the ventilation portion 51 can be set in consideration of the balance between the amount of heat and water vapor that can be discharged from the ventilation portion 51 and the suppression of dust from entering through the exhaust port 16s. Specifically, the number of ventilation holes 51a of the ventilation portion 51, the opening area of ​​each individual ventilation hole 51a, the total opening area of ​​all ventilation holes 51a included in the ventilation portion 51, etc. can be set in consideration of the above-mentioned balance.

[0121] like Figure 6As shown, in this example, each ventilation hole 51a has a circular shape, and its diameter is, for example, 3.5 mm. It should be noted that the shape and size of the ventilation hole 51a may be changed.

[0122] The ventilation portion 51 of this example is arranged so that three rows of ventilation holes 51a are arranged in the Z-axis direction, and in each row of ventilation holes, nineteen ventilation holes 51a are arranged in the X-axis direction (width direction). That is, the ventilation portion 51 includes a total of fifty-seven ventilation holes 51a. The width of the range in which the ventilation portion 51 is arranged in the X-axis direction (width direction) is 209 mm, which is larger than the width (206 mm) of the effective printing area of ​​the recording material P of the maximum size (LTR size).

[0123] Furthermore, the ventilation holes 51a are provided in the region between the plurality of rib shapes 42a of the double-sided rib 42 included in the rear door 14 in the X-axis direction (width direction). The ventilation holes 51a penetrate from the outer surface 14a to the inner surface 14b ( Figure 5 ).

[0124] Filters

[0125] The filter 50 included in the imaging device 100 of this example will be described. Figure 5 and Figure 6 As shown, the imaging device 100 includes a filter 50 provided to cover the ventilation portion 51. More specifically, at least one filter 50 covering each of the ventilation holes 51a of the ventilation portion 51 is attached to the inner surface 14b of the rear door 14. By providing the filter 50 covering the ventilation portion 51, as will be described later, the entry of dust through the ventilation holes 51a and the entry of dust through the exhaust port 16s can be suppressed.

[0126] It should be noted that in the present invention, foreign matter that can enter the interior of the imaging device 100 by being blown by the airflow flowing from the exterior to the interior of the imaging device 100 will be collectively referred to as "dust". Therefore, "dust" may be particles other than sand (for example, particles obtained from plastic or wood), or may include a variety of particles.

[0127] In the rear door 14 of this example, a plurality of ventilation holes 51a are respectively arranged in a plurality of regions formed between a plurality of rib shapes 42a of the double-sided rib 42. In the following description, a plurality of ventilation holes 51a arranged in one region between the rib shapes 42a adjacent in the X-axis direction will be referred to as a group of ventilation holes 51a. In this example, a group of ventilation holes 51a is arranged in each of the nine regions between the plurality of rib shapes 42a. In addition, a filter 50 is provided in each of the nine regions between the plurality of rib shapes 42a. The filter 50 arranged in each region covers all ventilation holes 51a of the group in the corresponding region. The imaging device 100 of this example includes a total of nine filters 50.

[0128] The filter 50 is made of a material having air permeability, moisture permeability, high heat resistance and moisture resistance. As the material of the filter 50, (1) a sponge material such as polyurethane foam, acrylic foam or melamine foam, or (2) a non-woven fabric formed of fibers such as cotton, polyethersulfone (PES), polyethylene terephthalate (PET) or glass can be used. In addition, as the material of the filter 50, (3) filter paper (paper filter) or (4) a metal filter formed of stainless steel or the like can be used. Since the performance required by the filter 50 changes according to various factors (such as the positional relationship between the fixing part 9 and the ventilation part 51, the adjustment temperature of the heater 113, the shape of the ventilation part 51, the expected use environment, etc.), the material, thickness, etc. of the filter 50 can be appropriately changed.

[0129] In this example, a filter obtained by compressing a moltopren (registered trademark) SM-55 sheet material (polyurethane foam manufactured by INOAC CORPORATION) to ½ in the thickness direction is used as the filter 50 .

[0130] The thickness of the filter 50 of this example is set so that the filter 50 does not come into contact with the recording material P conveyed in the double-sided conveying path CP2. Figure 5 As shown, at each position within the range in which the filter 50 is provided in the Z-axis direction, the thickness of the filter 50 is smaller than the protrusion amount of the rib shape 42a of the double-sided rib 42 relative to the inner surface 14b of the rear door 14. In other words, the thickness of the filter 50 is smaller than the minimum value H1 of the protrusion height of the double-sided rib 42 relative to the inner surface 14b of the rear door 14. The minimum value H1 of the protrusion amount of the rib shape 42a is, for example, 3.5 mm, and the thickness of the filter 50 is 1 mm.

[0131] When the filter 50 contacts the recording material P conveyed in the double-sided conveying path CP2, there is a possibility that the recording material P may be skewed or clogged, or the recording material P may be contaminated by droplets or foreign matter attached to the filter 50. By setting the thickness of the filter 50 to be smaller than the protruding height of the double-sided ribs 42, the possibility of such a problem can be reduced.

[0132] For example, the filter 50 is attached to the inner surface 14b of the rear door 14 by a double-sided tape or an adhesive. In the case where the filter 50 is attached to the inner surface 14b by a double-sided tape, it is preferred that the holes defined in the double-sided tape overlap with the ventilation portion 51 so as to suppress clogging of the ventilation portion 51 by the double-sided tape. Figure 6 As shown, the central filter 50 among the nine filters 50 covers more ventilation holes 51a than the other eight filters 50 and is wider in the X-axis direction than the other eight filters 50. Therefore, for the central filter 50, by setting the length of the central filter 50 in the Z-axis direction to be greater than the length of the other eight filters 50, the attachment of the central filter 50 in the wrong position (misassembly) can be reduced. That is, in a case where a plurality of filters 50 are provided and the length of a portion of the filter 50 in a predetermined direction is different from the length of the other filters 50, misassembly can be reduced by making the length of a portion of the filter 50 in a direction orthogonal to the predetermined direction different from the length of the other filters 50. As described above, the plurality of filters 50 may include a filter 50 having a first shape and a filter 50 having a second shape, the second shape being different from the first shape.

[0133] Airflow in imaging equipment

[0134] A description will be given of air flow in a case where air outside the imaging apparatus 100 (hereinafter referred to as outside air) flows into the inside of the imaging apparatus 100. Since the inside of the imaging apparatus 100 is an imperfectly sealed space, outside air flows therein due to the influence of wind or the like.

[0135] Reference Fig. 7A , Figure 7B , Fig. 8A and Figure 8B And Table 1 describes the airflow flowing into the interior of the imaging device 100. The arrows in the figure indicate the direction of the main airflow. The thickness of the arrow indicates the flow speed (wind speed), and the thicker the arrow, the higher the speed.

[0136] Fig. 7A and Figure 7B Each is a schematic diagram for describing the flow of air in the image forming apparatus 100 of the present example, in which the filter 50 is provided on the ventilation portion 51 . Fig. 8A and Figure 8BEach is a schematic diagram for describing the flow of air in an imaging device 500 of Comparative Example 1, in which a filter 50 is not provided on a ventilation portion 51. The imaging device 500 of Comparative Example 1 has the same configuration as the imaging device 100 of Example 1 except that the filter 50 is not provided on the ventilation portion 51.

[0137] Fig. 7A and Fig. 8A Each shows an air flow in a case where air is blown from the front side (+Y side) of the image forming apparatus 100 by using the blower 300 . Figure 7B and Figure 8B Each shows an air flow in a case where air is blown from the rear side (−Y side) of the image forming apparatus 100 by using the blower 300 .

[0138] Table 1 shows the measurement results of the wind speed at the measurement positions (F1 to F3) in the imaging device 100 in the case where the wind is blown from the front side or the rear side. SPCON-MAMAWM-SC manufactured by ONISHI ELECTRIC INDUSTRY CO., LTD. is used as the blower 300. In the case of blowing from the front side, the blower 300 is set so that the wind with a wind speed of 1m / s blows on the exhaust port 16s. In the case of blowing from the rear side, the blower 300 is set so that the wind with a wind speed of 1m / s blows on the ventilation part 51. It should be noted that even in the case where the blower 300 is set so that the wind with a wind speed of 1m / s blows on the exhaust port 16s, the wind speed of the wind blown into the imaging device 100 through the exhaust port 16s is not necessarily 1m / s, and is usually lower than 1m / s.

[0139] The wind speed in the imaging device 100 was measured by using a micro anemometer manufactured by Tohnic. Since this measuring device is capable of measuring wind speeds in the range of 0.1 m / s or more, the case where the wind speed is lower than the detection lower limit (0.1 m / s) of the measuring device is described as "<0.1" (m / s) in Table 1.

[0140] exist Fig. 7A , Figure 7B , Fig. 8A and Figure 8BA probe of an anemometer is set in each of the three measurement positions (F1 to F3) in the imaging device 100 shown in each of the figures. The first measurement position F1 is located near the discharge port 16s. The second measurement position F2 is a position near the ventilation portion 51, and upstream of the portion of the double-sided conveying path CP2 closest to the ventilation portion 51 in the recording material conveying direction. The third measurement position F3 is a position near the ventilation portion 51, and downstream of the portion of the double-sided conveying path CP2 closest to the ventilation portion 51 in the recording material conveying direction. Specifically, the probe at the second measurement position F2 is set on the upper surface of the double-sided guide 13, and the probe at the third measurement position F3 is set between the rib shapes 42a of the double-sided rib 42 located at a position below the ventilation portion 51.

[0141] Table 1

[0142]

[0143] First, refer to Fig. 8A A case is described in which wind blows from the front side (+Y side) onto the image forming apparatus 500 of Comparative Example 1. In this case, external air flows into the image forming apparatus 500 through the discharge port 16s, and an amount of air corresponding to the amount of external air that has flowed in is discharged to the outside of the image forming apparatus 500 through the ventilation portion 51 and the inlet port 6s. The air that has flowed into the image forming apparatus 500 through the discharge port 16s mainly passes through the space on the upper side of the double-sided guide 13, and flows to the outside of the image forming apparatus 500 through the ventilation portion 51 (path K11).

[0144] In Comparative Example 1, the path to the ventilation portion 51 through the space on the upper side of the discharge port 16s and the double-sided guide 13 in the imaging device 500 is a space similar to an air duct, which does not have many steep curves or narrow parts. When the air flows into the imaging device 500 through the discharge port 16s, the air in the conveying path CP is pushed toward the ventilation portion 51 and is transferred to the outside of the imaging device 500 through the ventilation portion 51. Therefore, airflow is generated at the first measurement position F1 and the second measurement position F2 located on the above-mentioned path. As shown in Table 1, in Comparative Example 1, in the case where the wind with a wind speed of 1 m / s is blown from the front side, the wind speed at the first measurement position F1 is 0.41 m / s, and the wind speed at the second measurement position F2 is 0.27 m / s.

[0145] The reason why the wind speed at the second measurement position F2 above the double-sided guide 13 is lower than the wind speed at the first measurement position F1 near the discharge port 16s is that the space or member existing between the first measurement position F1 and the second measurement position F2 generates resistance to the airflow. That is, a part of the air passing through the first measurement position F1 flows back in the main conveying path CP1 to the space around the fixing portion 9. In addition, the conveying guide and the rib shape existing between the first measurement position F1 and the second measurement position F2 interrupt the airflow and thereby generate resistance.

[0146] In addition, in Comparative Example 1, the wind speed at the third measurement position F3 is lower than the detection lower limit. A portion of the air that has passed through the second measurement position F2 is discharged to the outside of the housing 101 (the outside of the imaging device 500) through the inlet port 6s for receiving the recording material P from the feeding portion 6. However, the path from the second measurement position F2 to the inlet port 6s is longer than the path from the second measurement position F2 to the ventilation portion 51. In addition, since the double-sided rib 42 and the U-shaped guide 43 exist on the path from the second measurement position F2 to the inlet port 6s, the space through which the air can pass is narrow in the path from the second measurement position F2 to the inlet port 6s, and the resistance to the airflow is large. Therefore, it can be considered that, in Comparative Example 1, most of the air that has passed through the second measurement position F2 is discharged through the ventilation portion 51, and only a very small amount of air reaches the inlet port 6s through the path K12.

[0147] Next, we will refer to Figure 8B A case is described in which air is blown from the rear side (-Y side) onto the imaging device 500 of Comparative Example 1. In this case, external air flows into the imaging device 500 through the ventilation portion 51, and an amount of air corresponding to the amount of external air that has flowed in is discharged to the outside of the imaging device 500 through the discharge port 16s and the inlet port 6s.

[0148] Due to the above reasons, air flows more easily in the path from the ventilation portion 51 to the exhaust port 16s than in the path from the ventilation portion 51 to the inlet port 6s. Therefore, the wind speed at the second measurement position F2 is higher than the wind speed at the third measurement position F3. As shown in Table 1, in the case where the wind with a wind speed of 1m / s is blown from the rear side, the wind speed at the second measurement position F2 is 0.19m / s, and the wind speed at the third measurement position F3 is 0.11m / s. It should be noted that in the path from the ventilation portion 51 to the exhaust port 16s, the wind speed at the first measurement position F1 located downstream of the second measurement position F2 is 0.12m / s.

[0149] Next, we will refer to Fig. 7A In comparison with Comparative Example 1, air flow in the case where air is blown to the imaging apparatus 100 of Example 1 from the front side (+Y side) is described.

[0150] In this case, similar to Comparative Example 1, external air flows into the imaging apparatus 100 through the discharge port 16s, and an amount of air corresponding to the amount of external air that has flowed in is discharged to the outside of the imaging apparatus 100 through the ventilation portion 51 and the inlet port 6s.

[0151] It should be noted that in this example, since the filter 50 is provided on the ventilation portion 51, the air flow is less likely to pass through the ventilation portion 51 compared with Comparative Example 1. Therefore, compared with Comparative Example 1, the air flow (path K1) from the discharge port 16s through the space on the upper side of the double-sided guide 13 to the ventilation portion 51 is smaller than the air flow (path K2) corresponding to this in Comparative Example 1. Fig. 8A Path K11).

[0152] In this example, since the air flow is less likely to pass through the ventilation portion 51, the ratio of the air that has flowed in through the discharge port 16s and passed through the second measurement position F2, which flows to the inlet port 6s along the path K2 but does not flow to the ventilation portion 51, becomes high. However, as described above, in the path from the ventilation portion 51 to the inlet port 6s, since the double-sided rib 42 and the U-shaped guide 43 generate a reaction force, the air is less likely to move.

[0153] In the case where the wind blows from the front side, the wind speed at the first measurement position F1 near the discharge port 16s can be regarded as the wind speed of the wind blown into the conveying path CP through the discharge port 16s. As shown in Table 1, the wind speed (0.24 m / s) at the first measurement position F1 in the case where the wind blows from the front side in Example 1 is lower than the wind speed (0.41 m / s) at the first measurement position F1 in the case where the wind blows from the front side in Comparative Example 1. That is, the wind speed of the wind blown into the conveying path through the discharge port 16s in the case where the wind of a predetermined wind speed (for example, 1 m / s) blows from the outside of the imaging device 100 of Example 1 toward the discharge port 16s is lower than the wind speed of the wind blown into the conveying path through the discharge port 16s in the case where the wind of the predetermined wind speed blows from the outside of the imaging device 100 of Example 1 toward the discharge port 16s in the state where the filter 50 is removed from the imaging device 100 of Example 1 (Comparative Example 1).

[0154] As described above, in the case where the wind blows onto the imaging device 100 of Example 1 from the front side (+Y side), the air in the imaging device 100 is less likely to move as a whole than in Comparative Example 1. In other words, in Example 1, as a result of providing the filter 50 on the ventilation portion 51 in Example 1, when the wind blows from the front side, the air pressure in the imaging device 100 is higher than that in Comparative Example 1 in which the filter 50 is not provided. As a result, the outside air is less likely to flow into the imaging device 100, thereby reducing the entry of dust particles.

[0155] As shown in Table 1, in the case where the wind with a wind speed of 1 m / s blows on the imaging device 100 of this example, the wind speed at the first measurement position F1 is 0.24 m / s, and the wind speed at the second measurement position F2 is 0.15 m / s. These values ​​are lower than the wind speed at the first measurement position F1 and the wind speed at the second measurement position F2 in the case where the wind with a wind speed of 1 m / s blows from the front side in Comparative Example 1, respectively.

[0156] On the contrary, in the case where the wind with a wind speed of 1 m / s blows from the front side onto the imaging device 100 of the present example, the wind speed at the third measurement position F3 is 0.10 m / s. This value is higher than the wind speed at the third measurement position F3 in the case where the wind with a wind speed of 1 m / s blows from the front side in Comparative Example 1. This is because, in Comparative Example 1, almost all the air that has passed through the second measurement position F2 is exhausted through the ventilation portion 51, whereas in the present example, since the air is less likely to pass through the ventilation portion 51, the proportion of the air that flows toward the inlet port 6s is higher among the air that has passed through the second measurement position F2.

[0157] Next, we will refer to Figure 7B In comparison with Comparative Example 1, airflow in a case where wind blows onto the imaging apparatus 100 of Example 1 from the rear side (-Y side) is described.

[0158] In this case, similar to Comparative Example 1, external air flows into the imaging device 100 through the ventilation portion 51, and an amount of air corresponding to the amount of external air that has flowed in is discharged to the outside of the imaging device 100 through the discharge port 16s and the inlet port 6s.

[0159] It should be noted that in this example, since the filter 50 is provided on the ventilation portion 51, the air flow is less likely to pass through the ventilation portion 51 than in Comparative Example 1. Therefore, the amount of air entering the interior of the imaging device 100 through the ventilation portion 51 is smaller than in Comparative Example 1. The air that does not enter the interior of the imaging device 100 through the ventilation portion 51 hits the outer surface 14a of the rear door 14 and then diffuses (arrows K3 and K4). As a result, as shown in Table 1, in each of the measurements at the first measurement position F1, the second measurement position F2, and the third measurement position F3, the wind speed is lower than the detection lower limit.

[0160] Here, as the external environment where the imaging apparatus 100 is actually located, a case where wind from an air conditioner or outdoor wind is blown and dust is contained in the wind is considered.

[0161] Dust contained in the external air also moves in the imaging device 100 along with the airflow in the imaging device 100 generated by the external air blowing in. Therefore, there is a case where dust accumulates in the path of the air flow. When the airflow is strong, that is, when the wind speed is high, the dust is more likely to move due to being blown by the wind. In addition, the possibility of dust movement also depends on the size of dust particles, and there is a tendency that dust is more likely to move due to being blown by the wind when the particles are smaller.

[0162] In the room where the image forming apparatus 100 is installed, there is a case where an air flow generated by an air conditioning device or a blowing device flows through the space connecting the discharge port 16s and the ventilation portion 51 to each other. In the case where the image forming apparatus 100 is used in an environment where a lot of dust exists in the air and the air flow flowing through the space connecting the discharge port 16s and the ventilation portion 51 to each other is strong, the dust may enter the image forming apparatus 100 together with the outside air. In addition, when the photosensitive drum 1 and the fixing film 112 of the fixing portion 9 are damaged by the dust that has entered the image forming apparatus 100, and component breakage or image defects occur, these components need to be replaced.

[0163] As described above, in this example, since the filter 50 is provided on the ventilation portion 51, external air is less likely to enter the interior of the imaging device 100 through the discharge port 16s and the ventilation portion 51. Therefore, dust can be suppressed from entering the imaging device 100 along with the external air.

[0164] An experiment conducted to examine the effect of providing the filter 50, such as suppression of dust entry, will be described below.

[0165] Dust particle size and ingress potential

[0166] First, the inventors conducted an experiment to examine Fig. 9A and Fig. 9B How many dust particles of different sizes can enter the imaging device 100 under the conditions shown. The blower is installed at a height of 21 cm from the floor surface on which the imaging device 100 is installed, which is the height of the exhaust port 16s of this example, and the wind blows toward the imaging device 100. Dust particles fall from above onto the air flow from the blower. The dust particles are moved to a position downstream of the falling position O0 in the direction of the wind by being blown by the wind. SPCON-MAMA WM-SC manufactured by ONISHI ELECTRIC INDUSTRY CO., LTD. is used as the blower. In the example shown in FIG. Fig. 9A In the case where the image forming apparatus 100 is blown from the front side (+Y side) as shown, the blower is set so that the wind of 1 m / s blows on the discharge port 16s, that is, the wind speed at the position O1 of the discharge port 16s is 1 m / s. Fig. 9BIn the case where the image forming apparatus 100 is blown from the rear side (-Y side), the blower is set so that wind of 1 m / s blows on the ventilation portion 51, that is, the wind speed at position O1 of the ventilation portion 51 is 1 m / s.

[0167] In the experiment, crystal powder (hereinafter referred to as quartz particles) manufactured by NAKAGAWA GOFUN ENOGU CO., LTD. was used as an example of dust particles. The fineness grades (indicating the grade of particle fineness) of the quartz particles were #8, #7, and #6. As a result of observing the quartz particles of each fineness grade using an optical microscope, the quartz particles of #8 had a particle size of 80 μm to 100 μm, the quartz particles of #7 had a particle size of 100 μm to 150 μm, and the quartz particles of #6 had a particle size of 150 μm to 200 μm. The amount of quartz particles blown was set to 0.2 g. In addition, experiments were conducted for both the case where the wind blew onto the imaging device 100 from the front side and the case where the wind blew onto the imaging device 100 from the rear side.

[0168] In the case where quartz particles of each fineness grade were blown toward the image forming apparatus 100 by wind, the number of quartz particles attached to the fixing portion 9 and the double-sided guide 13 in the image forming apparatus 100 was counted. Table 2 shows the results thereof.

[0169] Table 2

[0170]

[0171]

[0172] In Example 1, in both the case where the wind blows from the front side and the case where the wind blows from the rear side, when the particle diameter of the quartz particles is larger, the quartz particles are less likely to adhere to the fixing portion 9 and the double-sided guide 13. That is, when the particle diameter of the quartz particles is larger, the quartz particles are less likely to enter the interior of the image forming apparatus 100 by being blown by the wind.

[0173] In the case of conducting a similar experiment by using the imaging device 500 of Comparative Example 1, the number of quartz particles entering the inside of the imaging device 100 increased for quartz particles of each fineness grade compared to Example 1 regardless of the direction of the wind.

[0174] For example, in the case where a wind of 1 m / s blows from the front side onto the imaging device 500 of Comparative Example 1, as described above, the wind speed at the first measurement position F1 near the discharge port 16s is 0.41 m / s, and the wind speed at the second measurement position F2 is 0.27 m / s. The quartz particles are moved into the imaging device 500 through the discharge port 16s by being blown by the wind configured in this manner, and are attached to the fixing portion 9 and the double-sided guide 13. Due to the airflow ( Fig. 8A The path K11) is strong, so most of the quartz particles that have entered the image forming apparatus 500 are accumulated on the double-sided guide 13. It should be noted that some quartz particles fall due to gravity in the middle of the path from the discharge port 16s to the ventilation portion 51, and move toward the fixing portion 9 (path K10).

[0175] As can be seen from the results of Table 2, according to Example 1, compared with Comparative Example 1, dust particles entering the imaging device 100 can be reduced.

[0176] As described above, the double-sided guide 13 (second guide portion) is located between the discharge port 16s and the ventilation portion 51 in the Y-axis direction. Therefore, for example, in a case where dust particles have entered from the outside of the imaging device 100 by being blown by wind blowing from the discharge port 16s to the ventilation portion 51, there is a possibility that part of the dust particles accumulate on the double-sided guide 13. In addition, since the double-sided guide 13 is curved into a convex shape that convexes upward, there is a case where, for example, dust particles accumulated on the double-sided guide 13 fall from the double-sided guide 13 along the curved surface when the rear door 14 is opened or closed. According to Example 1, since the entry of dust particles through the discharge port 16s or the ventilation portion 51 can be reduced, such a problem is less likely to occur.

[0177] In this example, the fixing film 112 is located between the discharge port 16s and the ventilation portion 51 in the Y-axis direction. In other words, when viewed in the width direction (X-axis direction) perpendicular to both the vertical direction and the discharge direction Dc, the fixing film 112 (film) is arranged between the discharge port 16s and the ventilation portion 51 (opening portion) in the direction (Y-axis direction) perpendicular to the vertical direction. In this arrangement, it can be considered that dust particles that have entered the interior of the imaging device 100 through the discharge port 16s or the ventilation portion 51 adhere to the fixing film 112 and accelerate the tearing of the fixing film 112. According to Example 1, since the entry of dust particles through the discharge port 16s or the ventilation portion 51 can be reduced, such a problem is less likely to occur.

[0178] When the photosensitive drum 1 is damaged, there is a case where an image defect in the shape of a black dot (referred to as a black dot image) appears in the image formed on the recording material P at a position corresponding to the damage of the photosensitive drum 1. In this example, the photosensitive drum 1 is located between the discharge port 16s and the ventilation portion 51 in the Y-axis direction. In other words, when viewed in the width direction (X-axis direction) perpendicular to both the vertical direction and the discharge direction Dc, the photosensitive drum 1 is arranged between the discharge port 16s and the ventilation portion 51 (opening portion) in the direction (Y-axis direction) perpendicular to the vertical direction. In this arrangement, a case can be considered in which dust particles that have entered the interior of the imaging device 100 through the discharge port 16s or the ventilation portion 51 adhere to the photosensitive drum 1 and thus an image defect such as a black dot image appears. According to Example 1, since the entry of dust particles through the discharge port 16s or the ventilation portion 51 can be reduced, such a problem is less likely to occur.

[0179] Fusing film tearing

[0180] Particles falling on the fixing portion 9 may damage the fixing film 112, and larger particles are more likely to damage the fixing film 112. When particles larger than 100 μm repeatedly reach the fixing portion 9, damage to the fixing film 112 accumulates, and there is a possibility that the fixing film 112 is torn before the cumulative sheet passing number of the image forming apparatus 100 reaches the service life sheet number. That is, the entry of dust particles can accelerate the tearing of the fixing film 112.

[0181] Whether the tearing of the fixing film 112 is accelerated is evaluated by the following experiment. Whenever 2000 sheets pass through the imaging device 100 or 500, when the blower blows air from the front side of the imaging device 100 or 500, quartz particles (fineness grade: #6) are dispersed in front of the discharge port 16s, and thus the quartz particles are intentionally allowed to enter the imaging device 100 or 500. As the recording material P, OCE RED LABEL 80gsm A4 paper is used. The blower is set so that the wind of 1m / s blows on the discharge port 16s. The amount of quartz particles to be dispersed is set to 0.5g. SPCON-MAMA WM-SC manufactured by ONISHI ELECTRIC INDUSTRY CO., LTD is used as the blower. The results are shown in Table 3.

[0182] Table 3

[0183]

[0184] As shown in Table 3, in Comparative Example 1, tearing of the fixing film 112 occurred when the cumulative sheet passing number reached 40,000. In contrast, in Example 1, tearing of the fixing film 112 did not occur even when the cumulative sheet passing number reached 50,000, which is the life sheet number of the image forming apparatus 100.

[0185] As described above, in the case where wind is blown on the image forming apparatus 100 of the present example from the front side (+Y side), the wind blowing into the image forming apparatus 100 is weaker than in Comparative Example 1 (Table 1). Therefore, even in the case where the quartz particles are scattered by the wind, the number of quartz particles entering the inside of the image forming apparatus 100 is less than that in Comparative Example 1 (Table 2). In particular, since the particles are less likely to be moved by the wind when the particles are larger, the larger-sized quartz particles that are more likely to damage the fixing film 112 are less likely to enter the inside of the image forming apparatus 100. As a result, it can be considered that in Example 1, the number of quartz particles reaching the fixing portion 9 is less than that in Comparative Example 1, and therefore the tearing of the fixing film 112 does not occur.

[0186] It should be noted that if Fig. 7A As shown by arrow K5 in FIG. 1 , in Example 1, it has been confirmed that most of the quartz particles fall on the frame 191 which is on the front side of the fixing portion 9. It can be considered that this is because the wind passing through the path from the discharge port 16s to the ventilation portion 51 is weak in Example 1, and thus the quartz particles fall at an earlier stage. In contrast, in Comparative Example 1 ( Fig. 8A ), since the wind passing through the path from the discharge port 16s to the ventilation portion 51 is strong, the quartz particles move farther, and thus the number of quartz particles falling onto the fixing portion 9 (path K10) increases.

[0187] As described above, particles larger than 100 μm are less likely to reach the fixing portion 9 in the image forming apparatus 100 of Example 1 than in Comparative Example 1. Therefore, particles larger than 100 μm are less likely to damage the fixing film 112. It is considered that, as a result thereof, the fixing film 112 is not torn in Example 1 even when the cumulative sheet passing number reaches the life sheet number of the image forming apparatus 100.

[0188] It should be noted that there are cases where the wind speed of the air blowing on the image forming apparatus 100 is higher than 1 m / s and cases where the wind speed is lower than 1 m / s. In the case where the wind speed is higher than 1 m / s, more and larger dust is more likely to be moved by the wind. However, since the filter 50 is provided on the ventilation portion 51 in this example, dust is less likely to be blown into the image forming apparatus 100 regardless of the wind speed, and tearing of the fixing film 112 and the like are less likely to occur compared to Comparative Example 1.

[0189] It should be noted that although the fixing film 112 has been mentioned as an example of a member damaged by dust particles that have entered the interior of the image forming apparatus 100 herein, since the entry of dust particles is suppressed, damage to members of the image forming apparatus 100 other than the fixing film 112 is also reduced. For example, a situation in which, due to the attachment of dust particles to the elastic layer (rubber layer) on the outer peripheral portion of the roller that conveys the recording material P, the wear of the roller is accelerated and the service life of the roller becomes shorter than expected can be suppressed.

[0190] Condensation suppression

[0191] How to maintain the function of the vent portion 51 to discharge heat and water vapor generated in the fixing portion 9 to the outside of the image forming apparatus 100 even in a case where the filter 50 is provided on the vent portion 51 will be described.

[0192] As a test for evaluating the water drop resistance of the imaging device 100, sheets left in an environment of room temperature of 32.5°C and humidity of 80% for 48 hours were set in the feeding section 6, double-sided printing was performed on 10 sheets of the sheets, and it was checked whether water drop traces could be observed on the image. It should be noted that the test was started after the internal temperature of the imaging device 100 became substantially equal to room temperature after a sufficiently long time had passed since the previous imaging operation was completed. This is because condensation is more likely to occur after the internal temperature returns to room temperature compared to a state in which the interior of the imaging device 100 is hot. The sheet used for the test was CS-680 manufactured by Canon. A halftone image with an image coverage of 25% was formed on the entire effective printing area of ​​each surface of each sheet.

[0193] During the duplex printing process, when water droplets accumulate somewhere on the duplex transport path CP2, the sheet passing through the duplex transport path CP2 comes into contact with the water droplets and becomes wet. Then, when the image is transferred from the photosensitive drum 1 to the second surface of the sheet, moisture is adsorbed onto the surface area of ​​the photosensitive drum 1 that has been in contact with the wet portion of the sheet. The surface area of ​​the photosensitive drum 1 on which moisture has been absorbed is charged more strongly by the charged portion than its surrounding area. In the surface area that is strongly charged by the charged portion, the concentration of the toner image formed by the exposure and development steps is lower than that of its surrounding area. As a result, in the halftone image transferred to the sheet, an image defect (called a water drop mark or a white spot image) occurs, in which a white spot appears at a position in the image corresponding to the surface area of ​​the photosensitive drum 1 that has been in contact with the wet portion of the sheet.

[0194] Fig.10 An example of a water drop mark is shown. The water drop mark is an image defect that appears periodically at intervals corresponding to the peripheral length of the photosensitive drum 1.

[0195] If the water vapor generated in the fixing portion 9 is effectively discharged to the outside of the image forming apparatus 100, water drop marks are less likely to occur. In the present embodiment, although minute water drop marks were observed on the second surfaces of two sheets out of ten sheets, no water drop marks were observed on the other sheets. Considering the fact that the test was conducted under severe conditions where water condensation may occur as described above, the above results indicate that water drop resistance performance sufficient for practical use is achieved.

[0196] As described above, according to the present example, even in the case where the filter 50 is provided on the ventilation portion 51, the function of the ventilation portion 51 to discharge heat and water vapor generated in the fixing portion 9 to the outside of the image forming apparatus 100 can be maintained. That is, by providing the filter 50 on the ventilation portion 51, it is possible to suppress dust from entering the image forming apparatus 100 through the discharge port 16s and the ventilation portion 51, while maintaining the function of the ventilation portion 51 to discharge heat and water vapor to the outside of the image forming apparatus 100.

[0197] Image defects caused by dust

[0198] When dust enters the interior of the image forming apparatus, dust particles adhere to the photosensitive drum 1 to cause image defects. This will be described.

[0199] As shown in Table 2, in the case where the external air including dust particles is blown onto the image forming apparatus 500 of Comparative Example 1, the dust particles are also accumulated on the double-sided guide 13. Fig.11 As shown, in the image forming apparatus 500 of Comparative Example 1, the photosensitive drum 1 and the double-sided guide 13 are arranged at a position between the ventilation portion 51 and the discharge port 16s in the front-rear direction (Y-axis direction) of the image forming apparatus 500. Therefore, when the rear door 14 is opened or closed in a state where the dust particles D1 are accumulated on the double-sided guide 13, the dust particles D1 fall from the double-sided guide 13 onto the photosensitive drum 1, as shown in FIG. Fig.11 As shown (arrow K6), this is mainly due to the vibration of the housing 101 when the rear door 14 is closed.

[0200] Furthermore, the housing 101 also vibrates when opening or closing the transfer guide unit 15. Since the transfer guide unit 15 of this example is urged toward the closed position by the spring member, the vibration of the housing 101 generated when closing the transfer guide unit 15 is strong. That is, due to the vibration of the housing 101 generated when closing the transfer guide unit 15, the dust particles D1 fall from the double-sided guide 13 onto the photosensitive drum 1 (arrow K6).

[0201] The image defects caused by dust particles entering the interior of the imaging device were evaluated by the following test. As test paper, OCE RED LABEL 80gsm A4 paper was used. Whenever 2,000 test papers were passed, 0.5g of quartz particles (the above-mentioned #6 crystal powder) were dispersed, and air was blown by a blower to intentionally allow the quartz particles to enter the imaging device. The blower was set so that when blowing, 1m / s of wind was blown from the front or rear side of the imaging device to the discharge port 16s or the ventilation part 51. In addition, according to the direction of wind blowing, the quartz particles were dispersed in front of the discharge port 16s or the ventilation part 51. Whenever 2,000 sheets were passed, the direction of the wind when the quartz particles were allowed to enter was alternately switched between the front side and the rear side. SPCON-MAMA WM-SC manufactured by ONISHIELECTRIC INDUSTRY CO., LTD was used as a blower. In addition, every time 1,000 sheets are passed, the rear door 14 and the transfer guide unit 15 are opened and closed to apply vibration to the image forming apparatus.

[0202] When the quartz particles dropped from the double-sided guide 13 damage the photosensitive drum 1, a black dot image may appear, such as Fig.12 For each scratch on the photosensitive drum 1, a black dot image repeatedly appears in the conveying direction of the recording material P at a pitch corresponding to the peripheral length of the photosensitive drum 1. A row of black dot images that appear periodically as described above will be defined as a black dot image. The test results are shown in Table 4.

[0203] Table 4

[0204]

[0205]

[0206] As shown in Table 4, in Comparative Example 1, one black dot image appeared when the cumulative sheet passing number reached 10,000. In addition, six black dot images appeared when the cumulative sheet passing number reached 50,000 (which is the life sheet number of the image forming apparatus 500).

[0207] In contrast, in Example 1, no black dot image appears even when the cumulative sheet passing number reaches 20,000. In addition, although one black dot image appears when the cumulative sheet passing number reaches 30,000, there are only two black dot images even when the cumulative sheet passing number reaches 50,000 (which is the life sheet number of the imaging device 100).

[0208] In the case of the image forming apparatus 100 of Example 1, since the filter 50 is provided on the ventilation portion 51, the outside air is less likely to be blown into the image forming apparatus 100 (particularly, into the conveying path CP) compared with Comparative Example 1 (Table 1). As a result, in both cases where the wind blows on the image forming apparatus 100 of Example 1 from the front side and the rear side, dust particles are unlikely to accumulate on the double-sided guide 13 (Table 2). In particular, in this example, dust particles larger than 100 μm are unlikely to accumulate on the double-sided guide 13. It is considered that, for this reason, even when the housing 101 vibrates due to, for example, closing the rear door 14 after a jam is removed, dust particles are unlikely to adhere to the surface of the photosensitive drum 1, and therefore image defects caused by dust particles are unlikely to occur.

[0209] It should be noted that the wind speed of the wind blowing onto the imaging device may be higher or lower than 1 m / s. In the case where the wind speed is higher than 1 m / s, more and larger dust is more likely to be blown by the wind. However, in this example, since the filter 50 is provided on the ventilation portion 51, dust is less likely to be blown into the imaging device 100, and therefore, image defects caused by dust particles are less likely to occur regardless of the wind speed, as compared to Comparative Example 1.

[0210] As described above, according to the present example, it is possible to provide an imaging device capable of suppressing entry of dust.

[0211] In this example, by providing the filter 50 on the ventilation portion 51 of the housing 101, the wind speed of the wind blown into the imaging device 100 through the exhaust port 16s can be reduced while maintaining the function of discharging heat and water vapor of the ventilation portion 51. Therefore, it is possible to reduce the dust particles that enter the imaging device 100 due to being blown by the wind blown into the imaging device 100 through the exhaust port 16s.

[0212] According to the present example, by providing the filter 50 on the ventilation portion 51, even if the filter 50 is not provided on the discharge port 16s, it is possible to suppress dust particles from entering the image forming apparatus 100 through the discharge port 16s.

[0213] It should be noted that, as long as the discharge of the recording material P through the discharge port 16s is not interrupted, an additional filter covering part or all of the discharge port 16s may be provided in addition to the filter 50. In this case as well, the advantages obtained by providing the filter 50 on the ventilation portion 51 in this example can be maintained.

[0214] Example 2

[0215] Next, Example 2 will be described. Fig.13 is a perspective view of an imaging device 200 according to Example 2, and Fig.14 It shows that from Fig.13The imaging device 200 according to Example 2 includes an intake fan 80 and an exhaust fan 90 as air blowing portions (intake portion and exhaust portion) for cooling various units in the imaging device 200.

[0216] The imaging device 200 according to Example 2 has substantially the same configuration as the imaging device 100 according to Example 1, except that the imaging device 200 includes an intake fan 80, an exhaust fan 90, and an element for forming a path for airflows generated by these fans. It is assumed that the elements denoted by the same reference numerals as those in Example 1 have substantially the same configuration and function as those described in Example 1 (unless otherwise specified), and portions different from Example 1 will be mainly described.

[0217] like Fig.14 As shown, the housing 101 of the imaging device 200 includes an intake fan 80 and an exhaust fan 90 .

[0218] The intake fan 80 is provided on the side surface portion on the left side (-X side) of the housing 101. In a state where the exterior member is attached to the housing 101, the intake fan 80 is covered by a side surface cover 101C serving as an exterior member ( Fig.13 ). An air intake port 54 which is a hole extending to the inside of the housing 101 is provided in the side surface cover 101C. The air intake port 54 is an opening of the housing 101 provided at a position different from the discharge port 16s and the ventilation portion 51 (opening portion).

[0219] The intake fan 80 draws air (arrow AW1) from the outside of the imaging device 200 through the intake port 54 of the side surface cover 101C. The wind from the intake fan 80 cools the circuit board 140 ( Fig.14 ). The circuit board 140 including the high-voltage power supply portion and the low-voltage power supply portion is easily heated, and it is preferable to suppress the temperature rise inside the imaging device 200 by blowing air to cool the circuit board 140. It should be noted that the high-voltage power supply portion of the circuit board 140 is, for example, the charging power supply, the developing power supply, and the transfer power supply described above. In addition, the low-voltage power supply portion of the circuit board 140 is, for example, a power supply unit that supplies power to a CPU of a controller that controls the operation of the imaging device 200, a motor used as a driving source included in the imaging device 200, and the like.

[0220] Even if the wind sucked by the intake fan 80 contains dust particles, the intake port 54 of the side surface cover 101C does not need to be equipped with a filter if the possibility of causing image defects or component breakage is sufficiently low. It should be noted that in order to further suppress the entry of dust particles, a filter covering the intake port 54 can be attached to the side surface cover 101C.

[0221] The exhaust fan 90 is provided inside the housing 101. The exhaust fan 90 is provided at a position above the image forming section 10 and below the discharge tray 17 ( Fig.16A ).

[0222] Reference FIG. 15A to FIG. 15C The details of the exhaust fan 90 are described. Fig.15A is a perspective view of the exhaust fan 90 . Fig. 15B It shows that from Fig.15A A perspective view of a state in which the holder cover 93 is omitted. Fig. 15C It shows that from Fig.15A A perspective view of a state in which the fan holder 92 is further omitted.

[0223] The exhaust fan 90 includes a rotary blade 91 , a fan holder 92 , a holder cover 93 , and a gear train 95 .

[0224] The rotating blade 91 includes a rotating shaft 91a and a plurality of blade portions 91b protruding from the rotating shaft 91a, and rotates around the central axis of the rotating shaft 91a. The exhaust fan 90 of this example is arranged so that the central axis of the rotating shaft 91a is parallel to the X-axis direction (the left-right direction of the imaging device 200). The rotating blade 91 is rotatably supported by a fan holder 92 ( Fig. 15B ). One gear of a gear train 95 is attached to an end portion of the rotating shaft 91a. The rotating blade 91 rotates by receiving a driving force input from a driving source via the gear train 95.

[0225] The holder cover 93 is supported by the fan holder 92, and defines a path for air flow together with the fan holder 92. In addition, a space (chamber) in which the blade portion 91b of the rotating blade 91 is accommodated is defined between the holder cover 93 and the fan holder 92. The rotating blade 91 of this example includes three blade portions 91b ( Fig. 15C ). The holder cover 93 and the fan holder 92 define three chambers that respectively accommodate the three blade portions 91b.

[0226] More specifically, the fan holder 92 and the holder cover 93 define an approximately cylindrical chamber extending in the axial direction of the rotating shaft 91a. A duct opening 92b for rotating the blades 91 to introduce air in the imaging device 200 into the chamber is provided in the end surface in the axial direction of each chamber. In addition, a duct opening (exhaust port 92a) is provided in the fan holder 92, and the duct opening is used to discharge the air discharged from each chamber by the rotating blades 91 to the outside of the imaging device 200. In this example, the exhaust port 92a opens upward (+Z side). The exhaust port 92a is an opening of the housing 101 provided at a position different from the exhaust port 16s, the ventilation portion 51 (opening portion) and the air inlet port 54.

[0227] In this example, the intake fan 80 introduces external air into the imaging device 200, and the exhaust fan 90 discharges air from the inside of the imaging device 200 to the outside. That is, the intake fan 80 and the exhaust fan 90 function as an air blowing portion that generates an airflow that enters the inside of the housing 101 from the outside through the intake port 54 and flows out from the inside of the housing 101 to the outside through the exhaust port 92a. It should be noted that an airflow that flows in a similar path may also be generated by only one of the intake fan 80 and the exhaust fan 90. In other words, the intake port 54 and the exhaust port 92a define a path through which air flows into the imaging device from the outside, and this path is different from a path (a path including the conveying path CP) through which air flows into the imaging device from the outside through the exhaust port 16s or the ventilation portion 51.

[0228] It should be noted that the intake fan 80 and the exhaust fan 90 are basically operated when the imaging device 200 is operating, and the airflow generated by the intake fan 80 and the exhaust fan 90 is not generated when the imaging device 200 is not operating. The period in which the imaging device 200 is operating includes a period in which the imaging device 200 performs an imaging operation and a period in which the imaging device 200 stands by in a state (standby state) in which the imaging operation can be started immediately when the imaging device 200 receives a command to perform an imaging operation. The period in which the imaging device 200 is not operating includes a period in which the main power of the imaging device 200 is turned off and a period in which the imaging device 200 stands by in a state (sleep state) in which the imaging operation cannot be started immediately when the imaging device 200 receives a command to perform an imaging operation even when the main power is turned on.

[0229] Airflow in imaging equipment

[0230] Reference Fig.16A , Fig. 16B , Fig.17A and Fig. 17B Describes a phenomenon in which external air flows into an image forming apparatus in an inactive state. Fig.16A is a schematic diagram showing a state in which wind blows from the front side (+Y side) onto the imaging device 600 of Comparative Example 2 in an inactive state.

[0231] Fig. 16B is a schematic diagram showing a state in which wind blows from the rear side (-Y side) onto the imaging device 600 of Comparative Example 2 in the inactive state. Fig.17A is a schematic diagram showing a state in which wind blows from the front side (+Y side) onto the imaging device 200 of Example 2 in the inactive state. Fig. 17Bis a schematic diagram showing a state in which wind blows from the rear side (-Y side) onto the imaging device 200 of Example 2 in an inactive state. It should be noted that the imaging device 600 according to Comparative Example 2 has the same configuration as the imaging device 200 according to Example 2 except that the filter 50 is not provided on the ventilation portion 51.

[0232] The imaging devices 200 and 600 have an air intake port 54 ( Fig.13 ) and the exhaust port 92a of the exhaust fan 90. Therefore, as Fig.16A and Fig.17A As shown, when wind blows onto the imaging devices 200 and 600 from the front side (+Y side), external air is also blown into the imaging devices 200 and 600 through the exhaust port 92a of the exhaust fan 90. That is, in addition to the airflow (path K11) entering the inside of the imaging device 200 through the exhaust port 16s similarly to Example 1, an airflow (path K15) entering the inside of the imaging device 200 through the exhaust port 92a of the exhaust fan 90 is also generated.

[0233] Table 5 shows the measurement results of the air flow velocity, that is, the wind speed at each measurement position (F1 to F4) in the imaging device in the case where the wind blows from the front side or the rear side to the imaging device 200 and 600. The measurement was performed under the same measurement conditions as in Example 1 described in Reference Table 1. SPCON-MAMAWM-SC manufactured by ONISHI ELECTRIC INDUSTRY CO., LTD was used as the blower 300. In the case of blowing from the front side, the blower 300 was set so that the wind with a wind speed of 1m / s was blown on the exhaust port 16s. In the case of blowing from the rear side, the blower 300 was set so that the wind with a wind speed of 1m / s was blown on the ventilation part 51. The wind speed in the imaging device was measured by using a micro anemometer manufactured by Tohnic. Since the measuring device is capable of measuring wind speeds in a range above 0.1m / s, the case where the wind speed is lower than the detection lower limit (0.1m / s) of the measuring device is described as "<0.1" (m / s) in Table 5.

[0234] exist Fig.16A , Fig. 16B , Fig.17A and Fig. 17B The probe of the anemometer is set at each of the four measurement positions (F1 to F4) in the imaging devices 200 and 600 shown. The first measurement position F1, the second measurement position F2, and the third measurement position F3 are the same as those in Example 1, so their description will be omitted. The fourth measurement position F4 is between the duct openings 92b on the intake side of the exhaust fan 90 (between the chambers adjacent in the axial direction of the rotating blades 91, see Fig. 15C ).

[0235] Table 5

[0236]

[0237] As shown in Table 5, in the case where the wind of 1 m / s blows from the front side onto the imaging device 600 of Comparative Example 2, the wind speed at the first measurement position F1 is 0.53 m / s, and the wind speed at the second measurement position F2 is 0.29 m / s. That is, in the case where the wind of 1 m / s blows from the front side onto the imaging device 600 of Comparative Example 2, the wind speed near the discharge port 16s and near the uppermost portion of the double-sided guide 13 is higher than the case where the wind of 1 m / s blows from the front side onto the imaging device 500 of Comparative Example 1. This is because, in addition to the ventilation portion 51 and the inlet port 6s, a part of the air flowing into the imaging device 600 through the discharge port 16s is also discharged through the air intake port 54 of the side surface cover 101C, and therefore the air is more likely to flow in through the discharge port 16s.

[0238] Furthermore, in the case where the wind of 1 m / s blows from the front side onto the imaging device 600 of Comparative Example 2, the wind speed at the fourth measurement position F4 is 0.38 m / s. That is, when the wind hits the imaging device 600 from the front side, part of the air flows into the imaging device 600 through the exhaust port 92a of the exhaust fan 90 ( Fig.16A The air flowing into the image forming apparatus 600 through the exhaust port 92a of the exhaust fan 90 is discharged to the outside of the image forming apparatus 600 through the air intake port 54 of the side surface cover 101C.

[0239] In contrast, in the case where the wind of 1 m / s blows from the front side onto the imaging device 200 of Example 2, the wind speed at the first measurement position F1 is 0.34 m / s, and the wind speed at the second measurement position F2 is 0.17 m / s. That is, in Example 2, in the case where the wind blows from the front side onto the imaging device 200, the airflow generated in the conveying path CP in the imaging device 200 is weaker than that in Comparative Example 2. This is because the filter 50 is provided on the ventilation portion 51 (which serves as a main discharge path of the wind blown into the conveying path CP through the discharge port 16s in Comparative Example 2), and therefore the air does not easily pass through the ventilation portion 51.

[0240] That is, in the case where the wind blows onto the imaging apparatus 200 of Example 2 from the front side (+Y side), the air in the conveying path CP is less likely to move than the air in Comparative Example 2. In other words, in Example 2, as a result of providing the filter 50 in the ventilation portion 51, when the wind blows from the front side, the air pressure in the imaging apparatus 200 (particularly, in the space in the conveying path CP) is higher than the air pressure in Comparative Example 2 in which the filter 50 is not provided. As a result, the outside air is less likely to flow into the imaging apparatus 200.

[0241] Furthermore, in the case where the wind of 1 m / s blows from the front side onto the imaging device 200 of Example 2, the wind speed at the fourth measurement position F4 is 0.45 m / s. That is, when the wind hits the imaging device 200 from the front side, part of the air flows into the imaging device 200 through the exhaust port 92a of the exhaust fan 90 ( Fig.17A In addition, in the case where a wind of 1 m / s is blown from the front side to the imaging device 200 of Example 2, the measurement position with the highest wind speed is the fourth measurement position F4.

[0242] The air flowing into the image forming apparatus 200 through the exhaust port 92a of the exhaust fan 90 is discharged to the outside of the image forming apparatus 200 through the air intake port 54 of the side surface cover 101C. It should be noted that the photosensitive drum 1 and the fixing film 112 are not present on the path K15. Therefore, even if the air flowing into the image forming apparatus 200 through the exhaust port 92a of the exhaust fan 90 includes dust particles, the possibility of image defects or damage to components is low.

[0243] In the case where the wind of 1 m / s blows from the rear side onto the imaging device 600 of Comparative Example 2, the wind speed at the second measurement position F2 is 0.24 m / s, and the wind speed at the third measurement position F3 is 0.11 m / s. In contrast, in the case where the wind of 1 m / s blows from the rear side onto the imaging device 200 of Example 2, both the wind speed at the second measurement position F2 and the wind speed at the third measurement position F3 are lower than the detection lower limit. This is because in Comparative Example 2, the filter 50 is not provided on the ventilation portion 51, so the outside air flows in through the ventilation portion 51, while in Example 2, the filter 50 is provided on the ventilation portion 51, so the outside air is less likely to flow in through the ventilation portion 51.

[0244] Dust particle size and ingress potential

[0245] An experiment was conducted to examine how many dust particles of different sizes could enter the interior of the imaging device 200 in the configurations of Example 2 and Comparative Example 2. Experimental Conditions and References Fig. 9A and Fig. 9B The described Example 1 is the same as the Comparative Example 1. Table 6 shows the experimental results.

[0246] Table 6

[0247]

[0248]

[0249] The general tendency of Comparative Example 2 is that the number of particles accumulated on the fixing portion 9 and the double-sided guide 13 is smaller when the wind blows to the image forming apparatus from the front side than that of Comparative Example 1. Fig.16A As shown, this is an effect of the configuration in which the path through which the air flows into the imaging device 600 in Comparative Example 2 is branched into two. That is, in Comparative Example 2, the path through which the air flows into the imaging device 600 is branched into a path K10 extending from the discharge port 16s to the ventilation portion 51 and a path K15 extending from the exhaust port 92a of the exhaust fan 90 to the air intake port 54 of the side surface cover 101C. Therefore, in the case where quartz particles are scattered by the wind blowing on the imaging device 600 from the front side, part of the quartz particles are blown by the wind blown in the path K15 and enter the inside of the imaging device 600. The amount of quartz particles that enter the inside of the imaging device 600 by being blown by the wind blown in the path K10 extending through the conveying path CP is reduced by this amount.

[0250] In Example 2, in the case where air is blown to the image forming apparatus from the front side, the number of particles accumulated on the fixing portion 9 and the double-sided guide 13 is even smaller than that in Comparative Example 2. This is because since the filter 50 is provided on the ventilation portion 51, air is less likely to pass through the ventilation portion 51, and the wind speed in the path K10 extending from the discharge port 16s to the ventilation portion 51 is reduced (Table 5).

[0251] Furthermore, in Example 2, in the case where air was blown to the image forming apparatus from the front side, the amount of particles accumulated on the fixing portion 9 and the double-sided guide 13 was smaller than that in Example 1. Fig.17AAs shown, this is the effect of the configuration in which the path through which the air flows into the imaging device 200 in Example 2 is branched into two. That is, in Example 2, the path through which the air flows into the imaging device 200 is branched into a path K1 extending from the discharge port 16s to the ventilation portion 51 and a path K15 extending from the exhaust port 92a of the exhaust fan 90 to the air intake port 54 of the side surface cover 101C. In addition, in the case where the air is blown from the front side to the imaging device 200 of Example 2, the wind speed in the path K15 (see F4 of Table 5) is higher than the wind speed in the path K1 (see F1 and F2 of Table 5). Therefore, in the case where the quartz particles are scattered by the wind blown from the front side onto the imaging device 200 of Example 2, most of the quartz particles are blown by the wind blown in the path K15 and enter the inside of the imaging device 200. The amount of the quartz particles that enter the inside of the imaging device 200 by being blown by the wind blown in the path K1 extending through the conveying path CP is reduced by this amount.

[0252] Note that in Example 2, when air was blown to the image forming apparatus from the rear side, no particles were observed to accumulate on the fixing portion 9 and the double-sided guide 13. This is because the filter 50 suppressed the quartz particles from entering the image forming apparatus through the ventilation portion 51.

[0253] Fusing film tearing

[0254] For Examples 1 and 2 and Comparative Examples 1 and 2, experiments were conducted under the same conditions as those of Example 1 described with reference to Table 3 as to whether or not the tearing of the fixing film 112 was accelerated.

[0255] Table 7

[0256] Sheet count when film tears Comparative Example 1 40,000 Example 1 No tearing Comparative Example 2 45,000 Example 2 No tearing

[0257] As shown in Table 7, in Comparative Example 2, tearing of the fixing film 112 occurred when the cumulative sheet passing number reached 45,000. In contrast, in Example 2, tearing of the fixing film 112 did not occur even when the cumulative sheet passing number reached 50,000, which is the life sheet number of the image forming apparatus 200.

[0258] It can be considered that in Comparative Example 2, since the number of quartz particles accumulated on the fixing portion 9 is less than that in Comparative Example 1 in the case where wind is blown onto the image forming apparatus from the front side, the tearing of the fixing film 112 is less likely to occur than in Comparative Example 1. However, in the configuration of Comparative Example 2, a certain amount of quartz particles accumulate on the fixing portion 9, and as a result, the tearing of the fixing film 112 occurs before the number of life sheets is reached. In contrast, it can be considered that in Example 2, since the number of quartz particles accumulated on the fixing portion 9 is even less than that in Comparative Example 2 (Table 6), the tearing of the fixing film 112 does not occur.

[0259] Image defects caused by dust

[0260] Regarding image defects caused by dust particles entering the inside of the imaging device, a test was conducted under the same conditions as those of Example 1 and Comparative Example 1 described with reference to Table 4. The results are shown in Table 8.

[0261] Table 8

[0262]

[0263] As shown in Table 8, in Comparative Example 2, one black dot image appeared when the cumulative sheet passing number reached 20,000. In addition, three black dot images appeared when the cumulative sheet passing number reached 50,000 (which is the life sheet number of the image forming apparatus 600).

[0264] In contrast, in Example 2, no black dot image appears even when the cumulative sheet passing number reaches 30,000. In addition, although one black dot image appears when the cumulative sheet passing number reaches 40,000, there is only one black dot image even when the cumulative sheet passing number reaches 50,000 (which is the life sheet number of the imaging device 200).

[0265] In the case of the image forming apparatus 200 of Example 2, since the filter 50 is provided on the ventilation portion 51, the outside air is less likely to flow into the image forming apparatus 200 (particularly into the conveying path CP) than in Comparative Example 2 (Table 5). As a result, in both cases where wind blows on the image forming apparatus 200 from the front side and the rear side, dust particles are less likely to accumulate on the double-sided guide 13 (Table 6). In particular, in Example 2, dust particles larger than 100 μm are unlikely to accumulate on the double-sided guide 13. It is considered that, for this reason, even when vibration of the housing 101 occurs due to, for example, closing the rear door 14 after a jam is removed, dust particles are unlikely to adhere to the surface of the photosensitive drum 1, and therefore image defects caused by dust particles are unlikely to occur.

[0266] That is, also in the configuration of Example 2 in which the air intake port 54 and the air exhaust port 92 a are provided in the housing 101 , by providing the filter 50 on the ventilation portion 51 , the occurrence of image defects caused by dust particles can be suppressed.

[0267] Furthermore, in Example 2, the frequency of occurrence of black dot images is lower than that in Example 1. This is because in Example 2, the path of air flowing into the imaging device 200 in Example 2 is branched into the path K1 extending from the discharge port 16s to the ventilation portion 51 and the path K15 extending from the exhaust port 92a of the exhaust fan 90 to the air intake port 54 of the side surface cover 101C. Furthermore, this is because in the case where the imaging device 200 of Example 2 is blown from the front side, the wind speed in the path K15 (see F4 of Table 5) is higher than the wind speed in the path K1 (see F1 and F2 of Table 5). For these reasons, even if the wind blowing on the imaging device 200 from the front side includes dust particles, the number of dust particles that enter the inside of the imaging device 200 by being blown by the wind blown in the path K1 is less than that in Example 1. As a result, it can be considered that the frequency of occurrence of black dot images in Example 2 is even lower than that in Example 1.

[0268] As described above, according to the present example, it is possible to provide an imaging device capable of suppressing entry of dust.

[0269] In this example, by providing the filter 50 on the ventilation portion 51 of the housing 101, the wind speed of the wind blown into the imaging device 200 through the discharge port 16s can be reduced while maintaining the function of discharging heat and water vapor of the ventilation portion 51. Therefore, it is possible to reduce the dust particles from entering the imaging device 200 due to being blown by the wind blown into the imaging device 200 through the discharge port 16s, and thus it is possible to reduce the occurrence of image defects or component damage caused by the dust particles.

[0270] According to the present example, by providing the filter 50 on the ventilation portion 51, even if the discharge port 16s is not provided with the filter 50, it is possible to reduce the dust particles from entering the image forming apparatus 200 through the discharge port 16s.

[0271] Furthermore, according to the present example, in the case where wind blows onto the image forming apparatus 200 from the front side, there are a plurality of paths through which wind blows into the image forming apparatus 200. Therefore, in combination with providing the filter 50 on the ventilation portion 51, accumulation of dust particles on the fixing portion 9 and the double-sided guide 13 can be further suppressed, thereby suppressing tearing of the fixing film 112 and occurrence of image defects.

[0272] Other embodiments

[0273] In Examples 1 and 2, the filter 50 is provided on the inner surface 14b of the rear door 14, that is, on a surface further inside than the outer surface of the housing 101 ( Figure 5 and Figure 6 ). The configuration is not limited thereto, and as Fig.18As shown, the filter 50A can be provided on the outer surface 14a of the rear door 14, that is, on the outer surface of the housing 101. According to this configuration, even in the case where the filter 50A is thick, contact between the filter 50A and the recording material P conveyed in the conveying path CP in the housing 101 can be avoided, and thus the degree of freedom of selection of the filter 50A is improved. In addition, instead of a configuration in which a plurality of filters 50 are provided between a plurality of rib shapes 42a to avoid the double-sided rib 42 as in Example 1, one filter 50A that is longer in the X-axis direction (width direction) can be used, and thus the filter 50A can be attached more easily.

[0274] In Examples 1 and 2, the configuration in which a plurality of mutually independent ventilation holes 51a as the ventilation portion 51 are arranged in the X-axis direction (width direction) has been described as an example. The configuration is not limited to this, and as Fig.19 As shown, the ventilation portion 51' may include a ventilation hole 51a' extending in the X-axis direction (width direction). In this case, the installation range of the ventilation portion 51' in the X-axis direction (width direction) is set to a range from one end 51a1' to the other end 51a2' of the ventilation hole 51a' in the X-axis direction (width direction) (the opening range of the ventilation hole 51a'). The installation range of the ventilation portion 51' is preferably a range overlapping with a passing area of ​​a recording material P of the maximum size on which an imaging device can form an image. In addition, the installation range of the ventilation portion 51' is preferably a range including an effective printing area of ​​a recording material P of the maximum size.

[0275] In addition, if Fig.19 As shown, in the case of a configuration in which the ventilation portion 51' includes ventilation holes 51a' extending in the X-axis direction (width direction), for example, the filter 50' may be one filter covering the entire ventilation holes 51a' in the longitudinal direction.

[0276] In each of the above examples, the image forming section 10 as an electrophotographic unit of a direct transfer system that forms a monochrome image (black and white image) has been described as an example of an image forming section. The configuration is not limited thereto, and the image forming section may be an electrophotographic unit that forms a color image by using toners of a plurality of colors. In addition, the image forming section may be an electrophotographic unit of an intermediate transfer system in which a toner image formed on the photosensitive drum 1 is transferred to an intermediate transfer member such as an intermediate transfer belt by a primary transfer, and then the toner image is transferred from the intermediate transfer member to a recording material P by a secondary transfer. It should be noted that, in the case of an intermediate transfer system, the intermediate transfer member and a transfer device (primary transfer roller, secondary transfer roller, etc.) that performs primary transfer and secondary transfer correspond to a transfer unit.

[0277] In each of the above examples, the fixing portion 9 of the film heating system in which the tubular film (fixing film 112) is used as the heating member (fixing member) that heats the toner image has been described as an example of the fixing portion. The configuration is not limited to this, and the fixing portion may have a configuration of a heating roller system in which a cylindrical roller (fixing roller) having rigidity is used as the heating member (fixing member). In addition, the heating portion that heats the heating member (fixing member) is not limited to a ceramic heater, and may be, for example, a halogen lamp that emits radiant heat, or a coil unit that generates an alternating magnetic field for generating Joule heat by inducing current in a conductive layer of the heating member (fixing member).

[0278] In each of the above examples, the space inside the housing 101 communicating with the ventilation portion 51 has a function as a conveyance path for the recording material P. However, in the case of applying the technology of the present disclosure to an imaging device, the space inside the housing 101 communicating with the ventilation portion 51 does not necessarily have to function as a conveyance path.

[0279] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An imaging device, comprising: an image forming section configured to form a toner image on a recording material; a fixing portion configured to form a nip portion that clamps the recording material, and configured to fix the toner image onto the recording material by heating the toner image while conveying the recording material with the nip portion; a housing which accommodates the image forming section and the fixing section and in which a conveying path through which the recording material passes is formed; as well as a discharge portion configured to discharge the recording material to the outside of the housing in a discharge direction intersecting the vertical direction, wherein the housing includes a first outer surface and a second outer surface, the first outer surface facing the discharge direction and provided with a discharge port through which the recording material discharged by the discharge portion passes, and the second outer surface facing a direction opposite to the discharge direction and provided with an opening portion, the outside of the housing and the inside of the housing communicating with each other through the opening portion, wherein at least a portion of the discharge port and at least a portion of the opening portion are located above an upper end position of the clamping portion in the vertical direction, wherein the imaging device further comprises a filter arranged to cover the opening portion, and wherein in a width direction perpendicular to both the vertical direction and the discharge direction, the center of the transport path is located between one end and the other end of a range in which the opening portion is provided.

2. The imaging device according to claim 1, wherein the opening portion includes a plurality of openings arranged at different positions in the width direction, and The range of the opening portion in the width direction is a range from a first opening to a second opening, the first opening is an opening closest to the one end in the width direction among the multiple openings, and the second opening is an opening closest to the other end in the width direction among the multiple openings.

3. The imaging device according to claim 1, wherein the opening portion includes an opening extending in the width direction, and The range in which the opening portion is provided in the width direction is a range from one end of the opening to the other end of the opening in the width direction.

4. The imaging device according to claim 1, The length from one end to the other end of the range in which the opening portion is set in the width direction is more than 50% of the length of the maximum size of the recording material in the width direction, and the length of the maximum size of the recording material in the width direction is the largest among the recording materials on which the imaging device can form an image.

5. The imaging device according to claim 1, wherein the housing comprises an outer member and an opposing portion, the outer member having a second outer surface and an inner surface disposed on an opposite side of the second outer surface, and the opposing portion is opposed to the inner surface of the outer member with a gap therebetween, and A space continuous with the gap and the outside of the housing are in communication with each other through the opening portion.

6. The imaging device according to claim 5, wherein the outer member has a rib shape protruding in a direction from the inner surface toward the opposing portion and extending in a direction intersecting the width direction, wherein the filter is attached to the inner surface at a position different from the rib shape in the width direction, and Wherein at each position in a range in which the filter is arranged along the vertical direction, a thickness of the filter is smaller than a protrusion amount of the rib shape relative to the inner surface.

7. The imaging device according to claim 5, The exterior member is movable to a closed position where a main body opening provided in the housing is closed and an open position where the main body opening is opened.

8. The imaging device according to claim 5, The gap is a conveying path through which the recording material passes.

9. An imaging device comprising: an image forming section configured to form a toner image on a recording material; a fixing section configured to form a nip portion that clamps the recording material and to heat the toner image at the nip portion while conveying the recording material, thereby fixing the toner image to the recording material; a housing which accommodates the image forming section and the fixing section and in which a conveying path through which the recording material passes is formed; as well as a discharge portion configured to discharge the recording material to the outside of the housing in a discharge direction intersecting the vertical direction, wherein the housing includes a first outer surface and a second outer surface, the first outer surface facing the discharge direction and provided with a discharge port through which the recording material discharged by the discharge portion passes, and the second outer surface facing a direction opposite to the discharge direction and provided with an opening portion, the outside of the housing and the conveying path in the housing being connected to each other through the opening portion, wherein at least a portion of the discharge port and at least a portion of the opening portion are located above an upper end position of the clamping portion in the vertical direction, and The imaging device further includes a filter arranged to cover the opening portion.

10. The imaging device according to claim 9, Wherein, in the width direction perpendicular to both the vertical direction and the discharge direction, the opening portion is arranged within a range overlapping with a passing area of ​​a recording material of a maximum size, and the length of the recording material of the maximum size in the width direction is the largest among the recording materials on which the imaging device can form an image.

11. The imaging device according to claim 10, wherein the opening portion includes a plurality of openings arranged at different positions in the width direction, and The range in which the opening portion is set is a range from a first opening to a second opening, the first opening is an opening among the multiple openings that is closest to one end of the opening portion in the width direction, and the second opening is an opening among the multiple openings that is closest to the other end of the opening portion in the width direction.

12. The imaging device according to claim 10, wherein the opening portion includes an opening extending in the width direction, and The range in which the opening portion is provided in the width direction is a range from one end of the opening in the width direction to the other end of the opening in the width direction.

13. The imaging device according to claim 10, The length of the range in which the opening portion is provided from one end thereof to the other end in the width direction is 50% or more of the length of the largest-sized recording material in the width direction.

14. The imaging device according to claim 9, The housing includes an outer member having a second outer surface and an inner surface disposed on an opposite side of the second outer surface, and a first guide portion that is opposite to the inner surface of the outer member and defines a portion of the conveying path together with the outer member.

15. The imaging device according to claim 14, wherein the exterior member has a rib shape that protrudes in a direction from the inner surface toward the first guide portion and extends in a recording material conveying direction in the conveying path, wherein the filter is attached to the inner surface at a position different from the rib shape in a width direction orthogonal to both the vertical direction and the discharge direction, and Wherein at each position in a range in which the filter is arranged along the vertical direction, a thickness of the filter is smaller than a protrusion amount of the rib shape relative to the inner surface.

16. The imaging device according to claim 14, wherein the outer member is movable to a closed position in which a main body opening provided in the housing is closed and an open position in which the main body opening is opened, and in, In a state in which the exterior member is in the open position, the recording material is allowed to be removed from the portion of the conveying path through the main body opening.

17. The imaging device according to claim 9, The transmission path includes: a first conveying path through which the recording material passes when an image is formed on the recording material by the image forming section; and a second conveying path which branches off from the first conveying path and through which, in the case where an image is formed on a second surface of the recording material opposite to the first surface, the recording material on the first surface of which a toner image has been formed by the image forming section is again conveyed toward the image forming section, wherein the housing includes a second guide portion defining the second conveying path and being bent to have a convex shape convex upward when viewed in a width direction orthogonal to both the vertical direction and the discharge direction, and wherein the second guide portion is provided between the discharge port and the opening portion in a direction perpendicular to the vertical direction when viewed in the width direction.

18. The imaging device according to any one of claims 1 to 17, wherein the fixing portion includes a tubular film configured to contact the recording material at the nip portion and a heating portion configured to heat the film, and wherein the film is disposed between the discharge port and the opening portion in a direction perpendicular to the vertical direction when viewed in the width direction.

19. The imaging device according to any one of claims 1 to 17, wherein the image forming part includes a photosensitive drum and a transfer unit configured to transfer a toner image formed on the photosensitive drum to the recording material, and wherein the photosensitive drum is disposed between the discharge port and the opening portion in a direction perpendicular to the vertical direction when viewed in the width direction.

20. The imaging device according to any one of claims 1 to 17, The housing further comprises: an air intake port provided at a position different from the exhaust port and the opening portion; an exhaust port provided at a position different from the exhaust port, the opening portion, and the intake port; as well as An air blowing portion is configured to generate an air flow that flows from the outside to the inside of the housing through the air intake port and flows from the inside to the outside of the housing through the air exhaust port.

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