Image forming apparatus

Abstract

To provide an image forming device with which, even when a relay duct is disposed while being bent with a large curvature, ambient air sent by a fan passes through the relay duct with a desired air flow.SOLUTION: As a relay duct that guides ambient air sent by a fan, bellows-shaped flexible tubes 183a-183d having a number of projections formed on their outer circumferential surfaces are used. When these flexible tubes 183a-183d are bent, they are restricted from being bent by the projections on the inside of the bending (compression side) and can hardly be folded. Therefore, even when the flexible tubes 183a-183d are bent, they can retain the size of the cross section as compared with the situation before the bending, and can guide the ambient air without a change in air flow per unit time. Therefore, use of these flexible tubes 183a-183d makes it possible to easily realize an improvement in the freedom of design of a developing device and the relay duct.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an image forming apparatus such as a printer, a copier, a facsimile machine, or a multifunction machine.

Background Art

[0002] In an image forming apparatus, a toner image is formed on an image carrier such as a photosensitive drum or an intermediate transfer belt, the toner image is transferred from the image carrier to a recording material, and then heat and pressure are applied by a fixing device to fix the toner image on the recording material. The image forming apparatus includes a developing device that forms a toner image on a photosensitive drum charged by a charger. The developing device circulates and conveys toner while stirring it by a conveyance screw in the developing device, and heat is generated according to this stirring operation of the toner. However, when the developing device becomes hot, the temperature of the toner rises, which causes image defects. Therefore, conventionally, a fan, an air pump, etc. have been provided to cool the developing device with outside air. Conventionally, it has been proposed to form a duct for guiding outside air toward the developing device using a flexible tube (Patent Document 1). In the apparatus described in Patent Document 1, the flexible tube is arranged so as to be curved with a small curvature. Also, a tube having elasticity has been proposed for cooling a heat generating portion by an air flow (Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, recently, for example, commercial image forming apparatuses that can form toner images on more recording materials in a shorter time have been used. In such apparatuses, in order to increase the amount of air per unit time and pass outside air therethrough, a large fan with a large air volume and a large-diameter tube are arranged. However, since various members are densely arranged inside the image forming apparatus and the space for routing the tube is limited, in some places, it is necessary to arrange the tube with a large curvature. However, conventionally, when arranging the tube with a large curvature, the tube may be crushed halfway, and there is a risk that the outside air will not pass through the tube with a desired air volume.

[0005] In view of the above problems, an object of the present invention is to provide an image forming apparatus in which outside air blown by a fan passes through a tube with a desired air volume when a duct is formed using a flexible tube.

Means for Solving the Problems

[0007] An image forming apparatus according to an embodiment of the present invention is an image forming apparatus that forms an image on a recording material, and includes a photoreceptor, a charging unit that charges the surface of the photoreceptor by corona discharge, A housing that supports the charging unit, an exterior cover that is provided on the front of the housing so as to be openable and closable, an inner cover unit that is disposed in the housing so as to face the inner surface of the exterior cover in a closed state, a fan that blows outside air, provided in the inner cover unit, and a flexible relay duct that guides the outside air blown by the fan toward the charging unit. The relay duct is a bellows-shaped cylindrical member having an uneven outer peripheral surface with convex portions formed along the circumferential direction, and the bending is restricted by the convex portions when bent.

Effects of the Invention

[0008] According to the present invention, when the outside air blown by the fan is guided using a flexible relay duct, the outside air blown by the fan can pass through the relay duct with a desired air volume.

Brief Description of the Drawings

[0009]

Figure 1

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Mode for Carrying Out the Invention

[0010] [First Embodiment] <Image Forming System> The schematic configuration of the image forming system including the image forming apparatus of the present embodiment will be described with reference to FIG. 1. The image forming system 1X shown in FIG. 1 includes an image forming apparatus 100 and a finisher apparatus 300. The image forming apparatus 100 and the finisher apparatus 300 are connected so as to be able to transfer the recording material S. In the present embodiment, the finisher apparatus 300 is a post-process unit that can be attached to the image forming apparatus 100 for function expansion, and can perform the post-processes described later on the recording material S on which the toner image is fixed by the image forming apparatus 100. The image forming apparatus 100 and the finisher apparatus 300 are connected so as to be able to transmit and receive data to and from each other through a communication interface capable of serial communication or parallel communication.

[0011] <Image Forming Apparatus> The image forming apparatus 100 is an electrophotographic tandem type full-color printer, and has a first housing 101a and a second housing 101b. In the first housing 101a, various devices such as an image forming unit 700 for realizing the steps until the recording material S is conveyed and the toner image is transferred, and various members are arranged.

[0012] On the other hand, various devices such as a fixing unit 800 that realizes the process of conveying the recording material S and fixing the toner image, and various members are arranged in the second housing 101b. Further, in the second housing 101b, a display unit capable of displaying various information on the front side and an operation unit 200 having keys and the like capable of inputting various information according to user operations are arranged. Note that an electrical equipment unit (not shown) having a power supply board may be arranged on the back side of the first housing 101a and the second housing 101b. In this specification, when the user operates the operation unit 200 to operate the image forming apparatus 100, the side where the user stands is referred to as the "front", and the opposite side is referred to as the "back". Also, the left side surface when viewed from the front is referred to as the "left side surface", and the right side surface when viewed from the front is referred to as the "right side surface".

[0013] The image forming apparatus 100 includes image forming units Pa, Pb, Pc, and Pd that form yellow, magenta, cyan, and black images, respectively. The image forming apparatus 100 forms a toner image on the recording material S according to an image signal read from a document by a document reading apparatus 190 or an image signal received from an external device (not shown) such as a personal computer.

[0014] In the case of this embodiment, an image forming unit 700 that forms a toner image on the recording material S is configured by the image forming units Pa to Pd, primary transfer rollers 24a to 24d, an intermediate transfer belt 130, a plurality of rollers 13 to 15, and a secondary transfer outer roller 11. Examples of the recording material S include papers such as plain paper, thick paper, rough paper, embossed paper, coated paper, plastic films, and cloth.

[0015] As shown in FIG. 1, the image forming units Pa to Pd are arranged side by side along the moving direction of the intermediate transfer belt 130. The intermediate transfer belt 130 is stretched over a plurality of rollers (13, 14, 15) and is moved in the direction of arrow R2. Then, the intermediate transfer belt 130 carries and conveys the toner image to be primarily transferred as described later. A secondary transfer outer roller 11 is arranged at a position facing the secondary transfer inner roller 14 that stretches the intermediate transfer belt 130 with the intermediate transfer belt 130 interposed therebetween, forming a secondary transfer unit T2 that transfers the toner image on the intermediate transfer belt 130 to the recording material S. A fixing unit 800 is arranged downstream of the secondary transfer unit T2 in the recording material conveyance direction.

[0016] On the lower side of the image forming apparatus 100, a plurality (here, two) of cassettes 10 accommodating the recording material S are arranged. These cassettes 10 accommodate recording materials S having different sizes and thicknesses, and the recording material S is selectively conveyed from any of the cassettes 10. The recording material S is conveyed from the cassette 10 through a conveyance path by a conveyance roller 16 toward a registration roller 12. Thereafter, by the registration roller 12 rotating in synchronization with the toner image formed on the intermediate transfer belt 130, the recording material S is conveyed toward the secondary transfer unit T2. Note that, not limited to the recording material S accommodated in the cassette 10, the recording material S placed on a manual feeding unit (not shown) may be conveyed.

[0017] The image forming units Pa, Pb, Pc, Pd have substantially the same configuration except that the developing colors of the toner images are different. Therefore, here, the yellow image forming unit Pa will be described as a representative, and the description of the other image forming units Pb, Pc, Pd will be omitted.

[0018] A cylindrical photosensitive drum 3a is disposed in the image forming unit Pa as a photosensitive member. The photosensitive drum 3a is rotationally driven by a motor (not shown). Around the photosensitive drum 3a, a charging device 2a as a charging unit, an exposure device La, a developing device 1a as a developing unit, a primary transfer roller 24a, and a drum cleaning device 4a are arranged.

[0019] A process of forming, for example, a full-color image by the image forming apparatus 100 will be described. First, when the image forming operation is started, the surface of the rotating photosensitive drum 3a is uniformly charged by the charging device 2a. The charging device 2a is, for example, a corona charger that irradiates charged particles associated with corona discharge to charge the surface of the photosensitive drum 3a to a uniform potential. Next, the photosensitive drum 3a is scanned and exposed by laser light corresponding to the image signal emitted from the exposure device La. Thereby, an electrostatic latent image corresponding to the image signal is formed on the surface of the photosensitive drum 3a. The electrostatic latent image formed on the photosensitive drum 3a is developed into a toner image, which is a visible image, by a developer containing toner and carrier accommodated in the developing device 1a. In the developing devices 1a to 1d, the developer is circulated and conveyed while being agitated by a conveying screw (not shown).

[0020] The toner image formed on the photosensitive drum 3a is primarily transferred to the intermediate transfer belt 130 at the primary transfer portion T1 formed between the primary transfer roller 24a disposed with the intermediate transfer belt 130 interposed therebetween. At this time, a primary transfer voltage is applied to the primary transfer roller 24a. The toner remaining on the surface of the photosensitive drum 3a after the primary transfer is removed by the drum cleaning device 4a.

[0021] Such operations are sequentially performed in the respective image forming portions Pa to Pd for yellow, magenta, cyan, and black, and the four-color toner images are superimposed on the intermediate transfer belt 130. Thereafter, the recording material S accommodated in the cassette 10 is conveyed to the secondary transfer portion T2 in accordance with the timing of forming the toner image. Then, by applying a secondary transfer voltage to the secondary transfer outer roller 11, the full-color toner image formed on the intermediate transfer belt 130 is collectively secondarily transferred to the recording material S. The toner remaining on the intermediate transfer belt 130 after the secondary transfer is removed by a belt cleaning device (not shown).

[0022] The recording material S onto which the toner image has been transferred is conveyed to the fixing unit 800. The fixing unit 800 fixes the toner image on the recording material S by applying heat and pressure to the recording material S onto which the toner image has been transferred. In the case of this embodiment, after applying heat and pressure to the recording material S with the first fixing device 81, heat and pressure can be selectively applied further with the second fixing device 91. The fixing unit 800 causes the recording material S to be conveyed toward the second fixing device 91 after passing through the first fixing device 81, or to be conveyed while avoiding the second fixing device 91 after passing through the first fixing device 81, which is switched by the fixing switching flapper 95.

[0023] The second fixing device 91 is disposed on the downstream side in the conveyance direction of the recording material S from the first fixing device 81. The second fixing device 91 is selectively used for purposes such as further imparting gloss to the toner image on the recording material S fixed by the first fixing device 81. For example, when the recording material S is coated paper such as glossy paper or synthetic paper, the recording material S that has passed through the first fixing device 81 is conveyed through the fixing route 30a so that fixing is performed by both the first fixing device 81 and the second fixing device 91. On the other hand, when the recording material S is uncoated paper such as plain paper, the recording material S that has passed through the first fixing device 81 is conveyed through the fixing bypass route 30b that avoids the second fixing device 91 so that fixing is performed by the first fixing device 81 while no fixing is performed by the second fixing device 91.

[0024] Since the above-described first fixing device 81 and second fixing device 91 may have the same configuration, the first fixing device 81 will be described as an example here. The first fixing device 81 includes a fixing roller 82 (or a fixing belt) that is rotatable in contact with the surface of the recording material S on which the toner image is fixed, and a pressure belt 83 (or a pressure roller) that is pressed against the fixing roller 82 to form a fixing nip portion. At least one of the fixing roller 82 and the pressure belt 83 is heated by a heater (not shown). The first fixing device 81 applies heat and pressure to the recording material S when sandwiching and conveying the recording material S on which the toner image is formed in the fixing nip portion formed by the fixing roller 82 and the pressure belt 83, thereby fixing the toner image on the recording material S.

[0025] In the case of this embodiment, the image forming apparatus 100 is capable of duplex printing. In the case of single-sided printing, the recording material S on which the toner image is fixed is conveyed to the discharge conveyance path 150 and discharged to the outside of the image forming apparatus 100. In the case of duplex printing, the recording material S on which the toner image is fixed is conveyed to the duplex reverse conveyance path 600. The duplex reverse conveyance path 600 is formed across the first housing 101a and the second housing 101b. In the duplex reverse conveyance path 600, the recording material S is reversed by a switchback operation, and the front and back surfaces of the recording material S are interchanged. The reversed recording material S is conveyed toward the registration roller 12, and is conveyed to the secondary transfer unit T2 in a state where the non-printed back surface side is directed toward the intermediate transfer belt 130 by the registration roller 12. In the secondary transfer unit T2, the full-color toner image formed on the intermediate transfer belt 130 is collectively secondarily transferred onto the recording material S (back surface side). Thereafter, the recording material S is fixed with the toner image by the fixing unit 800 and discharged to the outside of the image forming apparatus 100 with the immediately previously image-formed surface (image forming surface) facing upward. Note that the switching between the above-described discharge conveyance path 150 and the duplex reverse conveyance path 600 is performed by the conveyance switching flapper 160. In this embodiment, the fixing unit 800 is configured to include two fixing devices, but a configuration including only one fixing device may be used. Further, a configuration may be adopted in which the second housing 101b is provided with a cooling device for cooling the recording material S on which the toner image is fixed by the fixing unit 800.

[0026] A finisher device 300 is connected to the image forming apparatus 100 so as to be able to receive the recording material S, and the recording material S discharged from the image forming apparatus 100 is conveyed to the finisher device 300. The recording material S conveyed to the finisher device 300 is subjected to post-process treatments such as a punching process of making holes in the recording material S or a stapling process of binding a plurality of recording materials S together with a staple by the finisher device 300. In the finisher device 300, the punched recording material S is discharged to the upper discharge tray 301, and the bundle of the stapled recording materials S is discharged separately to the lower discharge tray 302.

[0027] Next, the external air flow configuration in the image forming apparatus 100 will be described. First, as a first embodiment, the air flow configuration for cooling the developing devices 1a to 1d will be described. FIG. 2(a) shows the image forming apparatus 100 with the front door open, and FIG. 2(b) shows the image forming apparatus 100 with the front door closed.

[0028] As shown in FIG. 2(a), on the front surface of the first housing 101a, a left front door 170a and a right front door 170b as exterior covers are provided so as to be openable and closable in a double-leaf manner as shown in the figure. An intake cover 171 is provided above the left front door 170a, and an intake port 171a is formed in the intake cover 171. Further, an inner cover 173 is provided inside the left front door 170a and the right front door 170b on the front surface of the first housing 101a. The inner cover 173 is for preventing the user from accidentally touching the movable parts, electrical wiring, etc. inside the first housing 101a when opening the front doors (170a, 170b). However, the inner cover 173 is detachably provided on the first housing 101a by screws or the like so that a service technician can perform maintenance work. An opening through which the image forming units Pa to Pd (shown by dotted lines) can be individually inserted and removed with respect to the first housing 101a is formed in the inner cover 173, and an inner cover unit 125 is detachably provided on the inner cover 173 so as to cover the image forming units Pa to Pd.

[0029] As shown in FIG. 2(b), on the left side surface of the first housing 101a, a left intake unit 124 having a fan (see FIG. 3 described later) for taking in external air from the intake port 171a is provided. In the case of this embodiment, the external air taken in from the intake port 171a is guided toward the image forming units Pa to Pd via the left intake unit 124 and the inner cover unit 125.

[0030] <Left intake unit> The left intake unit 124 will be described with reference to FIGS. 3 to 4(b). As shown in FIG. 3, the left intake unit 124 includes a left main body duct 174, a plurality of developing intake fans 180a, 180b, 180c, 180d for cooling the developing devices 1a to 1d supported by the first housing 101a, and side ducts 174a, 174b which will be described later. The left main body duct 174 is a duct having a space formed therein that communicates with the intake port 171a described above. In order to remove dust and the like from the outside air taken in from the intake port 171a, it is preferable to arrange a filter (not shown) in the middle of the flow path from the intake port 171a to the left main body duct 174.

[0031] On the right side surface of the left main body duct 174, as shown in FIG. 4(a), developing intake fans 180b, 180c, 180d and a side duct 174b are provided for cooling the developing devices 1b, 1c, 1d. A communication portion that communicates with the developing intake fans 180b, 180c, 180d is formed on the right side surface of the left main body duct 174, and the outside air taken in from the intake port 171a passes through the inside of the left main body duct 174 according to the operation of the developing intake fans 180b, 180c, 180d. A plurality of developing ducts (181b, 181c, 181d) are formed inside the side duct 174b. The side duct 174b is connected to the developing intake fans 180b, 180c, 180d so that the outside air that has passed through the developing intake fans 180b, 180c, 180d passes through each developing duct (181b, 181c, 181d).

[0032] On the left side of the left main body duct 174, in order to cool the developing device 1a, as shown in Fig. 4(b), a developing intake fan 180a and a side duct 174a are provided. Further, in the present embodiment, as will be described in detail later, charging intake fans 177a and 177b for sending outside air to the charging devices 2a and 2b (see Fig. 1) are provided. A communication portion communicating with the developing intake fan 180a, the charging intake fans 177a and 177b is formed on the left side surface of the left main body duct 174, and the outside air sucked from the intake port 171a according to the operations of the developing intake fan 180a, the charging intake fans 177a and 177b passes through the inside of the left main body duct 174. Inside the side duct 174a, a developing duct 181a and charging ducts 178a and 178b are formed. The side duct 174a is connected to the developing intake fan 180a, the charging intake fans 177a and 177b so that the outside air that has passed through the developing intake fan 180a, the charging intake fans 177a and 177b passes through each duct (181a, 178a, 178b).

[0033] Then, as shown in Fig. 3, the outside air sucked from the intake port 171a is sent to the developing devices 1a to 1d via the left main body duct 174, the developing intake fans 180a to 180d, the developing ducts 181a to 181d, and the inner cover unit 125.

[0034] <Inner cover unit> The inner cover unit 125 will be described with reference to Fig. 5. Fig. 5 is a schematic view showing the inner surface side of the inner cover unit 125. In the present embodiment, as shown in Fig. 5, flexible tubes 183a, 183b, 183c, and 183d are disposed on the inner surface side of the inner cover unit 125 as relay ducts through which outside air for cooling the developing devices 1a to 1d passes. The flexible tubes 183a to 183d are attached to the inner surface of the inner cover unit 125 using, for example, wire saddles.

[0035] On the inner surface side of the inner cover unit 125, inlet joints 182a, 182b, 182c, 182d and outlet joints 184a, 184b, 184c, 184d are provided so as to allow outside air to pass through. The inlet joints 182a to 182d as the first joint members are fixed at positions where each is connected to the outlets of the above-described developing ducts 181a to 181d. The outlet joints 184a to 184d as the second joint members are fixed at positions where each faces the developing devices 1a to 1d that can efficiently cool the developing devices 1a to 1d. The flexible tubes 183a to 183d have one end connected to the inlet joints 182a to 182d and the other end connected to the outlet joints 184a to 184d. Note that the routing of the flexible tubes 183a to 183d shown here is an example and is not limited to this.

[0036] The outside air sucked from the intake port 171a along with the operation of the developing intake fans 180a to 180d reaches the inlet joints 182a to 182d through the left main body duct 174 and the developing ducts 181a to 181d as described above. Thereafter, the outside air flows through the flexible tubes 183a to 183d and from the outlet joints 184a to 184d toward the developing devices 1a to 1d. In the present embodiment, on the inner surface side of the inner cover unit 125, the flexible tubes 183a to 183d can be appropriately curved and routed in a gap avoiding the flexible tubes 222a to 222d and the like that guide outside air to the charging devices 2a to 2d. That is, by using the flexible tubes 183a to 183d, the degree of freedom in duct arrangement within a limited space is increased.

[0037] Here, the air flow configuration after the outlet joints 184a to 184d will be described with reference to FIGS. 6(a) and 6(b). However, since the air flow configurations of the developing devices 1a to 1d are the same, the air flow configuration of the yellow developing device 1a is shown as an example here.

[0038] FIG. 6(a) is a front sectional view for explaining the air flow configuration of the developing device 1a, and FIG. 6(b) is a side sectional view for explaining the air flow configuration of the developing device 1a. As shown in FIG. 6(a), the developing device 1a includes an upper sleeve 210a, a lower sleeve 211a, and conveying screws 212a and 213a. The upper sleeve 210a and the lower sleeve 211a carry and rotate the developer to supply the developer to the photosensitive drum 3a. The conveying screws 212a and 213a circulate and convey the developer while stirring it in opposite directions within the developing device 1a.

[0039] Above such a developing device 1a, a developing cooling duct 186a is provided. Further, below the developing cooling duct 186a and above the conveying screw 212a, a heat sink 187 having a long shape in the front-rear direction (the direction of the rotation axis of the conveying screws 212a and 213a) is provided. The developing cooling duct 186a is arranged so as to be able to blow outside air closer to the conveying screws 212a and 213a than the upper sleeve 210a and the lower sleeve 211a with respect to the developing device 1a in a direction intersecting the rotation axis direction of the conveying screws 212a and 213a.

[0040] Also, as shown in FIG. 6(b), the developing cooling duct 186a is formed along the developing device 1a with respect to the rotation axis direction of the conveying screws 212a and 213a. The air that has passed through the outlet joint 184a is exhausted to the back side of the device through the developing cooling duct 186a. At this time, the heat sink 187 is cooled by the air flow passing through the developing cooling duct 186a. In this way, by cooling the heat sink 187 arranged above the conveying screw 212a, the developing device 1a that generates heat due to the rotation of the conveying screws 212a and 213a is indirectly cooled.

[0041] Next, the flexible tubes 183a to 183d, the inlet joints 182a to 182d, and the outlet joints 184a to 184d described above will be described with reference to FIGS. 7(a) to 10(c). Note that the inlet joints 182a to 182d and the outlet joints 184a to 184d may be the same. Hereinafter, the flexible tube 183a and the inlet joint 182a will be described as representative examples.

[0042] <Flexible tube> The flexible tube 183a is formed in a cylindrical shape with a hollow interior, and as shown in FIG. 7(a), it is a bellows-shaped cylindrical member in which a large number of convex portions 1831 are continuously formed on the outer peripheral surface at predetermined intervals. Alternatively, as shown in FIG. 7(b), the flexible tube 183a may be a bellows-shaped cylindrical member in which spiral convex portions 1832 are formed on the outer peripheral surface. In this way, the flexible tube 183a is a bellows-shaped cylindrical member having a continuous uneven outer peripheral surface on which convex portions 1831 (1832) are formed along the circumferential direction.

[0043] The inner peripheral surface of the flexible tube 183a may be an uneven surface in which concave portions 1833 are formed in accordance with the convex portions 1831 on the outer peripheral surface, as shown in FIG. 8(a). That is, the convex portion 1831 is hollow. Alternatively, the inner peripheral surface of the flexible tube 183a may be a flat surface without the above-described concave portions 1833, as shown in FIG. 8(b). In this case, the convex portion 1831 is not hollow.

[0044] Also, as shown in FIG. 9(a), the flexible tube 183a has a circular cross-section. Alternatively, as shown in FIG. 9(b), the flexible tube 183a may have a rectangular cross-section.

[0045] The above flexible tube 183a is a cylindrical member that is formed to be freely bendable using a resin such as PA6 (polyamide) or metal. As an example, for the flexible tube 183a, the desired air volume of the outside air passing through the flexible tube 183a is "0.1 m 3When it is " / min", it is formed with an inner diameter of "16 mm", a cross-sectional area of "about 200 mm 2 ", and a wall thickness of "0.1 mm". Further, the convex portion 1831 is formed so that the bending radius of the flexible tube 183a when bent is about "35 mm".

[0046] As shown in Fig. 10(a), when the flexible tube 183a is bent, on the outer peripheral surface of the curved outer side that becomes the tension side, tensile stress is applied to the convex portion 1831, so the convex portion 1831 deforms so that the corner at the tip and the corner at the base become obtuse angles. On the other hand, on the outer peripheral surface of the curved inner side that becomes the compression side, compressive stress is applied to the convex portion 1831, so the convex portion 1831 deforms so that the corner at the tip and the corner at the base become acute angles.

[0047] And the buckling limit in the plastic deformation of the flexible tube 183a on the tension side is determined by the elongation rate of the material used for the flexible tube 183a. Also, the buckling limit in the elastic deformation of the flexible tube 183a on the compression side is determined by the Young's modulus, tensile stress, and compressive stress of the material used for the flexible tube 183a. Further, on the compression side, when adjacent convex portions 1831 collide with each other and the flexible tube 183a cannot be bent any further, it becomes the buckling limit. In the case of this embodiment, at the buckling limit, the flexible tube 183a does not collapse and is in a state where the inner diameter before bending (for example, 16 mm) is maintained. That is, the bending of the flexible tube 183a is restricted by the convex portion 1831 on the inner side (compression side) of the bend when it is bent.

[0048] Specifically, the height of the convex portion 1831 of the flexible tube 183a is, for example, "2.5 mm or more and 7 mm or less", and the interval between adjacent convex portions 1831 is, for example, "2 mm or more and 5 mm or less". When such a flexible tube 183a is bent, the flexible tube 183a reaches the buckling limit with a bending radius of about "35 mm". Therefore, by changing the height of the convex portion 1831 of the flexible tube 183a and the interval between adjacent convex portions 1831 in advance, the buckling limit of the flexible tube 183a changes.

[0049] <Joint> Fig. 10(b) shows an example of the inlet joint 182a. Ducts are respectively connected to the air inlet and the air outlet of the inlet joint 182a. Taking a specific example, in the case of the inlet joint 182a, the developing duct 181a is connected to the inlet, and the flexible tube 183a is connected to the outlet. In the case of the outlet joint 184a, the flexible tube 183a is connected to the inlet, and the developing cooling duct 186a is connected to the outlet.

[0050] As shown in Fig. 10(b), the inlet joint 182a is formed such that the direction of the inlet and the direction of the outlet are, for example, 90 degrees different from each other in order to change the direction of the flowing outside air. In the present embodiment, the inlet joints 182a to 182d and the outlet joints 184a to 184d are formed so as to be able to connect the flexible tubes 183a to 183d curved with a curvature smaller than the bending limit.

[0051] Note that, as shown in Fig. 10(c), the flexible tube 183a is formed to have a free length before connection that is longer than the arrangement interval between the connected inlet joint 182a and outlet joint 184a. In this way, when the flexible tube 183a is connected to the inlet joint 182a and the outlet joint 184a, compressive stress is applied to both ends of the flexible tube 183a. Therefore, the flexible tube 183a is connected in a state of being in close contact with the inlet joint 182a and the outlet joint 184a.

[0052] As described above, in the present embodiment, as relay ducts for guiding outside air blown by the fan, flexible tubes 183a to 183d having a bellows shape with a large number of convex portions 1831 formed on the outer peripheral surface are used. When these flexible tubes 183a to 183d are bent, the convex portions 1831 restrict the bending on the inner side (compression side) of the bend, making it difficult to be bent. Therefore, even when the flexible tubes 183a to 183d are bent, the cross-sectional area is maintained compared to before bending, and the outside air can be guided without changing the air volume per unit time. Thus, by using the above flexible tubes 183a to 183d, it is easily possible to improve the design freedom of the developing devices 1a to 1d and the relay ducts.

[0053] Also, conventionally, it was necessary to mold a duct with a complex shape according to the air flow path, but in the present embodiment, such a necessity does not exist. Therefore, since the molds for molding the flexible tubes can be reduced and highly versatile flexible tubes (183a to 183d) can be manufactured at low cost, the cost can be reduced.

[0054] [Second Embodiment] Next, as a second embodiment, an air flow configuration related to the collection of scattered toner generated during the development of the toner image in the developing devices 1a to 1d will be described. In the image forming apparatus 100, the toner image is developed by supplying toner from the developing devices 1a to 1d to the photosensitive drums 3a to 3d. At this time, there is toner (referred to as scattered toner) that scatters without being supplied to the photosensitive drums 3a to 3d.

[0055] As shown in FIG. 6(a) described above, for example, in the developing device 1a, toner is supplied to the photosensitive drum 3a by the upper sleeve 210a and the lower sleeve 211a. However, the excess toner that is not supplied to the photosensitive drum 3a is collected into the agitation chamber 214. However, a part of the toner that is not supplied to the photosensitive drum 3a may scatter outside the developing device 1a without being collected into the agitation chamber 214. This scattered toner may stain the inside of the image forming apparatus 100 and cause image defects. Therefore, a toner collection unit is provided so that the scattered toner can be sent to the toner collection unit by the outside air and collected. Hereinafter, the developing device 1a will be described as a representative example.

[0056] As shown in FIGS. 11(a) and 11(b), the toner collection unit 400 includes an exhaust duct 217a, a developing exhaust fan 214a, and a toner collection filter 218a, and is disposed on the back side (the right side in FIG. 11(a)) of the first housing 101a. The developing exhaust fan 214a and the toner collection filter 218a are provided in the exhaust duct 217a. Below the lower sleeve 211a of the developing device 1a, a scattering collection duct 215a is disposed. The scattering collection duct 215a is formed along the axial direction of the lower sleeve 211a. A plurality of collection ports are formed in the scattering collection duct 215a so that the toner scattered below the lower sleeve 211a enters through these collection ports.

[0057] The scattering recovery duct 215a and the exhaust duct 217a of the toner recovery unit 400 are connected by a flexible tube 216a similar to the flexible tube 183a described above as a relay duct. The outside air containing the scattered toner is discharged to the outside of the image forming apparatus 100 through the flexible tube 216a and the exhaust duct 217a from the scattering recovery duct 215a by the air flow generated by the developing exhaust fan 214a. The toner recovery filter 218a is disposed in the middle of the flow path between the flexible tube 216a and the developing exhaust fan 214a. Therefore, the toner is removed from the outside air when passing through the toner recovery filter 218a, and the air from which the toner has been removed is discharged to the outside of the image forming apparatus 100.

[0058] Note that the above air flow configuration is the same in the developing devices 1a to 1d, and a flexible tube similar to the flexible tube 216a is provided as a relay duct. As a result, the same effects as those of the first embodiment described above, such as an improvement in the degree of freedom in designing the developing devices 1a to 1d and the ducts, can be obtained. Further, the flexible tube can be curved and disposed while maintaining the cross-sectional area without gaps in the ventilation path, and the outside air can be discharged to the outside of the image forming apparatus 100 without allowing the toner to escape while suppressing the pressure loss of the duct.

[0059] [Third Embodiment] Next, as a third embodiment, the air flow configuration in the charging devices 2a to 2d supported by the first housing 101a will be described. In FIG. 12, the charging device 2a is taken as a representative example. As shown in FIG. 12, in the charging device 2a, the air around the charging wire 203a is ionized by corona discharge to generate ions, thereby charging the surface of the photosensitive drum 3a. Since air is ionized to generate ions, it is necessary to blow outside air into the charging device 2a. In order to blow outside air into the charging device 2a, a primary intake duct 202a is disposed near the charging device 2a. Further, the charging device 2a generates not only ions but also ozone during corona discharge. However, since ozone easily corrodes, for example, a stainless steel grid (not shown) provided in the charging device 2a, it is necessary to recover it. Therefore, in order to send ozone to the ozone recovery filter 219a (see FIG. 17(a)) by outside air for recovery, a primary exhaust duct 204a is disposed near the charging device 2a.

[0060] As shown in FIG. 13, on the right side surface side of the first housing 101a, a right intake unit 126 having a fan (see FIG. 14 described later) for intake of outside air is provided, and outside air is taken in from the intake port 172a according to the operation of the fan. The intake port 172a is formed in a right cover 172 provided on the right side surface of the first housing 101a. The outside air taken in from the intake port 172a is guided to the charging devices 2c and 2d via the right intake unit 126 and the inner cover unit 125 by the charging intake fans 177c and 177d described later.

[0061] <Right intake unit> The right intake unit 126 will be described with reference to FIGS. 14 to 15(b). As shown in FIG. 14, the right intake unit 126 includes a right main body duct 176, charging intake fans 177c and 177d for blowing outside air to the charging devices 2c and 2d, and a passing duct 179 described later. The right main body duct 176 is a duct having a space formed inside that communicates with the above-described intake port 172a. In order to remove dust and the like from the outside air taken in from the intake port 172a, it is preferable to dispose a filter (not shown) in the middle of the flow path from the intake port 172a to the right main body duct 176.

[0062] On the left side surface of the right main body duct 176, as shown in FIG. 15(a), charging intake fans 177c and 177d for blowing outside air to the charging devices 2c and 2d are provided. That is, on the left side surface of the right main body duct 176, a communication portion that communicates with the charging intake fans 177c and 177d is formed, and the outside air taken in from the intake port 172a passes through the inside of the right main body duct 176 according to the operation of the charging intake fans 177c and 177d. And in the passing duct 179, as shown in FIG. 15(b), charging ducts 178c and 178d are formed inside. The passing duct 179 is connected to the charging intake fans 177c and 177d so that the outside air that has passed through the charging intake fans 177c and 177d passes through the charging ducts 178c and 178d.

[0063] The outside air taken in from the above-described intake port 172a is sent to the charging devices 2c and 2d via the right main body duct 176, the charging intake fans 177c and 177d, the charging ducts 178c and 178d, and the inner cover unit 125, as shown in FIG. 14. On the other hand, for the charging devices 2a and 2b, the outside air taken in from the above-described intake port 171a is sent via the left main body duct 174, the charging intake fans 177a and 177b, and the inner cover unit 125. Thus, in the present embodiment, the left intake unit 124 and the right intake unit 126 are used to blow outside air to the charging devices 2a to 2d.

[0064] <Inner cover unit> The inner cover unit 125 will be described with reference to FIG. 16. FIG. 16 is a schematic view showing the inner surface side of the inner cover unit 125. However, in FIG. 16, illustration of the flexible tubes 183a to 183d through which outside air for cooling the above-described developing devices 1a to 1d passes is omitted.

[0065] In the present embodiment, as shown in FIG. 16, flexible tubes 222a, 222b, 222c, and 222d, which are relay ducts through which outside air for blowing to the charging devices 2a to 2d passes, are disposed on the inner surface side of the inner cover unit 125. The flexible tubes 222a to 222d are attached to the inner surface of the inner cover unit 125 using, for example, wire saddles. The flexible tubes 222a to 222d are the same as the above-described flexible tube 183a.

[0066] Also, inlet joints 221a, 221b, 221c, and 221d and outlet joints 224a, 224b, 224c, and 224d are fixed to the inner surface side of the inner cover unit 125. The inlet joints 221a to 221d are fixed at positions where each is connected to the outlet of the above-described charging ducts 178a to 178d. The outlet joints 224a to 224d are fixed at positions where each faces the charging devices 2a to 2d capable of efficiently blowing outside air to the charging devices 2a to 2d. One end of each of the flexible tubes 222a to 222d is connected to the inlet joints 221a to 221d, and the other end is connected to the outlet joints 224a to 224d. Note that the routing of the flexible tubes 222a to 222d shown here is an example and is not limited thereto.

[0067] With the operation of the charging intake fans 177c and 177d, the outside air sucked in from the intake port 172a passes through the right main body duct 176 and the charging ducts 178c and 178d as described above, and reaches the inlet joints 221c and 221d. Also, with the operation of the charging intake fans 177a and 177b, the outside air sucked in from the intake port 171a passes through the left main body duct 174 and the charging ducts 178a and 178b as described above, and reaches the inlet joints 221a and 221b. Thereafter, the outside air passes through the flexible tubes 222a to 222d and flows from the outlet joints 224a to 224d to the charging devices 2a to 2d for each of the above primary intake ducts. In this way, by blowing the outside air to the charging devices 2a to 2d via the flexible tubes 222a to 222d, the charging devices 2a to 2d can form an air flow for recovering ozone generated by corona discharge for charging the photosensitive drums 3a to 3d.

[0068] In this way, together with the flexible tubes 183a to 183d for guiding the outside air to the developing devices 1a to 1d, the flexible tubes 222a to 222d for guiding the outside air to the charging devices 2a to 2d can be bent and stretched, so the degree of freedom in duct arrangement is high.

[0069] Next, the exhaust-side air flow configuration in the charging devices 2a to 2d will be described with reference to FIGS. 17(a) and 17(b). In FIGS. 17(a) and 17(b), the exhaust-side air flow configuration in the charging device 2a is shown as a representative example.

[0070] As shown in FIGS. 17(a) and 17(b), in order to remove the ozone generated along with the above-described corona discharge, an ozone recovery unit 500 is arranged on the back side (the right side in FIG. 17(a)) of the first housing 101a. The ozone recovery unit 500 includes an exhaust duct 217a that can be shared with the above-described toner recovery, a charging exhaust fan 220a, and an ozone recovery filter 219a. The charging exhaust fan 220a and the ozone recovery filter 219a are provided in the exhaust duct 217a.

[0071] The above-described primary exhaust duct 204a and the exhaust duct 217a of the ozone recovery unit 500 are connected by a flexible tube 223a similar to the flexible tube 183a described above as a relay duct. The outside air containing ozone described above is discharged to the outside of the image forming apparatus 100 through the flexible tube 223a and the exhaust duct 217a from the primary exhaust duct 204a by the air flow generated by the charging exhaust fan 220a. The ozone recovery filter 219a is disposed in the middle of the flow path between the flexible tube 223a and the charging exhaust fan 220a. Therefore, ozone is removed from the outside air when passing through the ozone recovery filter 219a, and the air from which ozone has been removed is discharged to the outside of the image forming apparatus 100.

[0072] Note that the above-described air flow configuration on the exhaust side has the same configuration in the charging devices 2a to 2d, and a flexible tube is provided as a relay duct. Thus, since the flexible tube is provided as a relay duct, the degree of freedom in duct arrangement is high also in the air flow configuration for ozone recovery. Further, it can be easily realized to arrange the flexible tube in a curved shape so as to suppress the pressure loss of the duct and prevent ozone from escaping.

[0073] <Other Embodiments> Note that in the above-described embodiment, the case of blowing outside air to the developing devices 1a to 1d and the charging devices 2a to 2d has been described as an example, but it is not limited thereto. For example, the above-described embodiment may be applied also when cooling a conveying member that conveys the recording material S after passing through the first fixing device 81 and the second fixing device 91 (see FIG. 1) with outside air.

[0074] Note that in the above-described embodiment, the electrophotographic image forming apparatus 100 has been described as an example, but it is not limited thereto. For example, the above-described embodiments may be applied also to image forming apparatuses of a heat drying system such as an inkjet printer and a sublimation printer.

Description of Reference Numerals

[0075] 1a... Developing unit (developing device), 2a... Charging unit (charging device), 3a... Photoconductor (photosensitive drum), 100... Image forming apparatus, 101a... Housing (first housing), 125... Inner cover unit, 170a, 170b... Exterior covers (left front door, right front door), 177a... Fan (charging intake fan), 180a... Fan (developing intake fan), 182a (221a)... First joint member (inlet joint), 183a (216a, 222a, 223a)... Relay duct (flexible tube), 184a (224a)... Second joint member (outlet joint), 214a... Fan (developing exhaust fan), 218a... Toner recovery filter, 219a... Ozone recovery filter, 220a... Fan (charging exhaust fan), 400... Toner recovery unit, 500... Ozone recovery unit, S... Recording material

Claims

1. An image forming apparatus for forming an image on a recording material, comprising: a photoreceptor; a charging unit for charging the surface of the photoreceptor by corona discharge; a housing for supporting the charging unit; an exterior cover provided on the front of the housing so as to be openable and closable; an inner cover unit disposed in the housing so as to face the inner surface of the exterior cover in a closed state; a fan for blowing outside air; a flexible relay duct provided in the inner cover unit for guiding the outside air blown by the fan toward the charging unit; wherein the relay duct is a bellows-shaped tubular member having an uneven outer peripheral surface with convex portions formed along the circumferential direction, and the bending is restricted by the convex portions when bent; An image forming apparatus characterized by the above.

2. a first joint member provided in the inner cover unit so that outside air can pass therethrough; a second joint member provided in the inner cover unit so that outside air can pass therethrough; wherein one end of the relay duct is formed so as to be connectable to the first joint member and the other end is formed so as to be connectable to the second joint member, and the free length before being connected to the first joint member and the second joint member is longer than the arrangement interval between the first joint member and the second joint member; The image forming apparatus according to claim 1, characterized by the above.

3. An ozone recovery unit having an ozone recovery filter connected to the charging unit so that outside air can pass therethrough and for recovering ozone generated during corona discharge when charging the photoreceptor in the charging unit; wherein the relay duct is connected to the ozone recovery unit for guiding the outside air blown by the fan to the ozone recovery filter; The image forming apparatus according to claim 1, characterized by the above.

4. wherein the relay duct has an uneven inner peripheral surface with the convex portions formed hollow; The image forming apparatus according to any one of claims 1 to 3, characterized by the above.

5. wherein the convex portions are formed in a spiral shape; The image forming apparatus according to any one of claims 1 to 4, characterized by the above.

6. wherein the relay duct is formed of metal so as to be bendable freely; The image forming apparatus according to any one of claims 1 to 5, characterized by the above.

7. wherein the relay duct is formed of resin so as to be bendable freely; The image forming apparatus according to any one of claims 1 to 6, characterized by the above.

Images